Ink jet ink, ink jet recording method, ink cartridge, recording unit and ink jet recording apparatus

ABSTRACT

An ink jet ink providing an image having excellent lightfastness and having sticking resistance and intermittent ejection stability. The ink jet ink is characterized by containing at least a compound represented by the following general formula (I) and a compound represented by the following general formula (II).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an ink jet ink, an ink jet recordingmethod, an ink cartridge, a recording unit and an ink jet recordingapparatus.

2. Description of the Related Art

The ink jet recording method is a recording method for forming an imageby applying small ink droplets onto recording mediums such as plainpaper and glossy medium. Because of cost reduction and improvement ofrecording speed, the ink jet recording method has been quickly andwidely used. Furthermore, the quality of the images obtained by the inkjet recording method has been improved and, in addition, digital camerashave been rapidly put in use. Accordingly, the ink jet recording methodis generally and widely used as a method of outputting an imagecorresponding to silver halide photography.

Recently, the size of ink droplets ejected by an ink jet system has beenreduced extremely small and a color range has been improved byintroduction of ink of multiple colors. By virtue of this, the qualityof the images obtained by the ink jet recording method has been muchimproved than ever. However, on the other hand, demands for coloringmaterials and ink have been more significant. Demands for propertiesthereof including color developability, clogging and reliability such asejection stability have been more stringent. In particular, ink to beapplied to the ink jet recording system, in which recording is performedby ejecting ink from a recording head by the action of thermal energy,is required to have the following properties: such as a property ofpreventing kogation of a recording head and a property of preventingwire breakage of a heater even if a predetermined number of electricpulses are applied, in short, required to have excellent recordingdurability.

Furthermore, the ink jet recording method has a problem in that fastnessproperties (image retainability) of the obtained image may not besufficient. Generally, the image obtained by the ink jet recordingmethod is not kept longer compared to a silver halide photograph. To bemore specifically, when an image recorded is exposed to light, moisture,heat and ambient gas present in the air for a long time, the coloringmaterial of the image deteriorates and problems such as color tonechange and color fading of the image are likely to occur. Particularly,fastness properties of an image recorded by use of ink containing a dyeas a coloring material are problems. Of them, in view of lightfastness,low lightfastness due to a chemical reaction intrinsic to the coloringmaterial is a problem. Of color inks such as cyan, magenta and yellowfrequently used in the ink jet recording method, magenta ink tends tohave low image fastness properties. With respect to magenta ink, studieshave been mostly conducted on dye thereof.

To solve the lightfastness problem, thereby improving the lightfastnessof an image, a number of proposals have been so far made in the art. Forexample, there is a proposal on magenta dye having a specific azostructure with high fastness properties and high color-developingproperty (see Japanese Patent Application Laid-Open No. 2006-143989).

Furthermore, for the purpose of improving reliability of ink to beapplied to the ink jet recording method, there is a proposal thatbis(2-hydroxyethyl)sulfone is added to ink (see Japanese PatentApplication Laid-Open No. H10-60347).

SUMMARY OF THE INVENTION

As the quality of an image by ink jet recording increases, the requisitelevel of fastness properties of image has been increased. Then, thepresent inventors conducted studies on ink containing a magenta dyedescribed in Japanese Patent Application Laid-Open No. 2006-143989above. However, it was found that the fastness properties of the imageobtained herein did not reach the level recently demanded. The presentinventors also conducted studies to improve the fastness properties ofan image to be recorded by use of the magenta dye-containing ink byusing a compound conventionally known to improve the fastness propertiesof an image. However, it was found that the use of such a compound andthe magenta dye in combination raises new problems described below.

First, it was found that clogging of ink occurs at the ejection port ofa recording head; in other words, sticking resistance of ink isinsufficient. In addition to this problem, when an ink jet recordingapparatus is allowed to stand still without ejecting ink for apredetermined time, moisture vaporizes from ink through an ejectionport. As a result, ink is not normally ejected, in other words, anintermittent ejection stability of ink is not sufficiently obtained.

Accordingly, an object of the present invention is to provide ink jetink, which forms an image (recorded by the ink) having excellentlightfastness and which has excellent sticking resistance andintermittent ejection stability. Another object of the present inventionis to provide ink jet ink having excellent recording durability even ifthe ink is applied to an ink jet recording system in which ink isejected by the action of thermal energy, and having a color tone thatcan be used as magenta ink. Another object of the present invention isto provide an ink jet recording method, an ink cartridge, a recordingunit, and an ink jet recording apparatus capable of stably providing animage having excellent lightfastness and high storage stability by useof the ink jet ink.

The aforementioned objects can be attained by the present invention asdescribed below. More specifically, the present invention is directed toink jet ink characterized by containing at least a compound representedby the following general formula (I) and a compound represented by thefollowing general formula (II):

wherein, in general formula (I), [A] is a 5-membered heterocyclic group;[B] and [C] are CR₁ and CR₂ or one of [B] and [C] is a nitrogen atom andthe other is CR₁; and R₅ and R₆ are each independently a hydrogen atomor a substituent selected from the group including an aliphatic group,an aromatic group, a heterocyclic group, an acyl group, analkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, analkylsulfonyl group, an arylsulfonyl group and a sulfamoyl group; ahydrogen atom of the substituent may be substituted; furthermore, R₁ andR₂ that can partly constitute [D], [B] and [C] in the formula are eachindependently a hydrogen atom or a substituent selected from the groupincluding a halogen atom, an aliphatic group, an aromatic group, aheterocyclic group, a cyano group, a carboxy group, a carbamoyl group,an alkoxycarbonyl group, an aryloxycarbonyl group, a heterocyclicoxycarbonyl group, an acyl group, a hydroxyl group, an alkoxy group, anaryloxy group, a heterocyclic oxy group, a silyloxy group, an acyloxygroup, a carbamoyloxy group, an alkoxycarbonyloxy group, anaryloxycarbonyloxy group, an amino group, an acylamino group, a ureidogroup, a sulfamoylamino group, an alkoxycarbonylamino group, anaryloxycarbonylamino group, an alkylsulfonylamino group, anarylsulfonylamino group, a heterocyclic sulfonylamino group, a nitrogroup, an alkylthio group, an arylthio group, a heterocyclic thio group,an alkylsulfonyl group, an arylsulfonyl group, a heterocyclic sulfonylgroup, an alkylsulfinyl group, an arylsulfinyl group, a heterocyclicsulfinyl group, a sulfamoyl group, and a sulfonic acid group; a hydrogenatom of the substituent may be substituted and R₁ and R₅ or R₅ and R₆may be joined to form a 5-membered ring or a 6-membered ring); and

R_(x)-[E]-R_(y)   General formula (II)

wherein, in general formula (II), -[E]- is —S—, —S(═O)— or —S(═O)₂—;R_(x) and R_(y) are each independently one selected from the groupincluding a hydrogen atom, a hydroxyl group, an alkyl group, ahydroxyalkyl group, an alkenyl group, an acyl group, a carbamoyl group,a carboxy group and a sulfonyl group, with the proviso that R_(x) andR_(y) may not simultaneously take hydrogen atoms or hydroxyl groups oran hydrogen atom and a hydroxyl group.

Furthermore, according to another aspect of the present invention, thereis provided an ink jet recording method for recording an image byejecting ink by an ink jet system, in which the ink is the ink jet inkhaving the aforementioned constitution.

Furthermore, according to another aspect of the present invention, thereis provided an ink cartridge provided with an ink storage portion forstoring ink, in which the ink is the ink jet ink having theaforementioned constitution.

Furthermore, according to another aspect of the present invention, thereis provided a recording unit having an ink storage portion for storingink and a recording head for ejecting ink, in which the ink is the inkjet ink having the aforementioned constitution.

Furthermore, according to another aspect of the present invention, thereis provided an ink jet recording apparatus having an ink storage portionfor storing ink and a recording head for ejecting ink, in which the inkis the ink jet ink having the aforementioned constitution.

According to the present invention, it is possible to provide ink jetink which forms an image having excellent lightfastness and which hasexcellent sticking resistance and intermittent ejection stability.Furthermore, according to another aspect of the present invention, it ispossible to provide ink jet ink having excellent recording durabilityeven if the ink is applied to an ink jet recording system in which inkis ejected by the action of thermal energy, and having the color tonethat can be used as magenta ink. As another embodiment of the presentinvention, it is possible to provide an ink jet recording method, an inkcartridge, a recording unit, and an ink jet recording apparatus usingthe ink jet ink.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an ink jet recording apparatus.

FIG. 2 is a perspective view of the machinery portion of the ink jetrecording apparatus.

FIG. 3 is a sectional view of the ink jet recording apparatus.

FIG. 4 is a perspective view illustrating how to install an inkcartridge in a head cartridge.

FIG. 5 is an exploded perspective view of the head cartridge.

FIG. 6 is a front view of a recording element substrate of the headcartridge.

DESCRIPTION OF THE EMBODIMENTS

The present invention will now be described in detail below withreference to exemplary embodiments. In the present invention, when acompound to be used is a salt, an expression of “salt is contained” isused for convenience, though at least a part of the salt is dissociatedto be an ion in an ink. Furthermore, in the following description,compounds represented by the general formulas (I) to (III) may besometimes described as “a compound of the general formula (I)”, “acompound of the general formula (II)” and “a compound of the generalformula (III)”, respectively.

<Ink>

Now, components constituting the ink jet ink according to the presentinvention (hereinafter, sometimes simply referred to as “ink”) andphysical properties of the ink will be more specifically described.

As a result of the studies conducted by the present inventors, it wasfound that when ink, which has a specific azo dye and a specificcompound in combination, is used, the image that is recorded by the inkhas excellent lightfastness, and that the ink has excellent stickingresistance and intermittent ejection stability. The present inventionwas on the basis of the findings and is characterized in that a specificazo dye and a specific compound are used in combination.

(Compound Represented by the General Formula (I))

It is necessary for the ink of the present invention to contain acompound of the following general formula (I) as a coloring material.

wherein, in general formula (I), [A] is a 5-membered heterocyclic group;[B] and [C] are CR₁ and CR₂ or one of [B] and [C] is a nitrogen atom andthe other is CR₁; and R₅ and R₆ are each independently a hydrogen atomor a substituent selected from the group including an aliphatic group,an aromatic group, a heterocyclic group, an acyl group, analkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, analkylsulfonyl group, an arylsulfonyl group and a sulfamoyl group; ahydrogen atom of the substituent may be substituted; furthermore, R₁ andR₂ that can partly constitute [D], [B] and [C] in the formula are eachindependently a hydrogen atom or a substituent selected from the groupincluding a halogen atom, an aliphatic group, an aromatic group, aheterocyclic group, a cyano group, a carboxy group, a carbamoyl group,an alkoxycarbonyl group, an aryloxycarbonyl group, a heterocyclicoxycarbonyl group, an acyl group, a hydroxyl group, an alkoxy group, anaryloxy group, a heterocyclic oxy group, a silyloxy group, an acyloxygroup, a carbamoyloxy group, an alkoxycarbonyloxy group, anaryloxycarbonyloxy group, an amino group, an acylamino group, a ureidogroup, a sulfamoylamino group, an alkoxycarbonylamino group, anaryloxycarbonylamino group, an alkylsulfonylamino group, anarylsulfonylamino group, a heterocyclic sulfonylamino group, a nitrogroup, an alkylthio group, an arylthio group, a heterocyclic thio group,an alkylsulfonyl group, an arylsulfonyl group, a heterocyclic sulfonylgroup, an alkylsulfinyl group, an arylsulfinyl group, a heterocyclicsulfinyl group, a sulfamoyl group, and a sulfonic acid group; a hydrogenatom of the substituent may be substituted and R₁ and R₅ or R₅ and R₆may be joined to form a 5-membered ring or a 6-membered ring).

In the general formula (I), [A] is a residue of a 5-memberedheterocyclic diazo component, [A]-NH₂. As the hetero atoms constitutingthe heterocyclic ring, N, O and S may be specifically mentioned. Ofthem, N can be contained in the 5-membered heterocyclic ring. Note thatthe heterocyclic ring may be joined with an aliphatic ring, an aromaticring or other heterocyclic rings by condensation. Examples of theheterocyclic ring include a pyrazole ring, an imidazole ring, a thiazolering, an isothiazole ring, a thiadiazole ring, a benzothiazole ring, abenzoxazole ring and a benzisothiazole ring. The heterocyclic group mayfurther have a substituent. Of them, a pyrazole ring, an imidazole ring,an isothiazole ring, a thiadiazole ring or a benzothiazole ringrepresented by the following general formulas (1) to (6) can be used.

In the general formulas (1) to (6), R₇, R₈, R₉, R₁₀, R₁₁, R₁₂, R₁₃, R₁₄,R₁₅, R₁₆, R₁₇, R₁₈, R₁₉ and R₂₀ represent the same elements as selectedas R₁ and R₂ constituting a part of [D] in the general formula (I)previously described. Of the general formulas (1) to (6), a pyrazolering or an isothiazole ring represented by the general formula (1) orthe general formula (2) can be used and particularly, a pyrazole ringrepresented by the general formula (1) can be used.

In the general formula (I), [B] and [C] are CR₁ and CR₂ or one of [B]and [C] is a nitrogen atom and the other is CR₁, R₅ and R₆ are eachindependently a hydrogen atom or a substituent selected from the groupdescribed below. The group of the substituents includes an aliphaticgroup, an aromatic group, a heterocyclic group, an acyl group, analkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, analkylsulfonyl group, an arylsulfonyl group and sulfamoyl group. Ahydrogen atom of the substituent may be substituted. R₅ and R₆ are anyone selected from the group including a hydrogen atom, an aliphaticgroup, an aromatic group, a heterocyclic group, an acyl group, analkylsulfonyl group and an arylsulfonyl group. Of them, a hydrogen atom,an aromatic group, a heterocyclic group, an alkylsulfonyl group or anarylsulfonyl group can be used, and particularly a hydrogen atom, anaryl group or a heterocyclic group can be used, with the proviso that R₅and R₆ may not simultaneously take a hydrogen atom. Each of thesubstituents may further have a substituent.

In the general formula (I), R₁ and R₂ that may constitute parts of [D],[B] and [C], each independently represents a hydrogen atom or asubstituent selected from the group described below. The group of thesubstituents includes a halogen atom, an aliphatic group, an aromaticgroup, a heterocyclic group, a cyano group, a carboxy group, a carbamoylgroup, an alkoxycarbonyl group, an aryloxycarbonyl group, a heterocyclicoxycarbonyl group, an acyl group, a hydroxyl group, an alkoxy group, anaryloxy group, a heterocyclic oxy group, a silyloxy group, an acyloxygroup, a carbamoyloxy group, an alkoxycarbonyloxy group, anaryloxycarbonyloxy group, an amino group, an acylamino group, a ureidogroup, a sulfamoylamino group, an alkoxycarbonylamino group, anaryloxycarbonylamino group, an alkylsulfonylamino group, anarylsulfonylamino group, a heterocyclic sulfonylamino group, a nitrogroup, an alkylthio group, an arylthio group, a heterocyclic thio group,an alkylsulfonyl group, an arylsulfonyl group, a heterocyclic sulfonylgroup, an alkylsulfinyl group, an arylsulfinyl group, a heterocyclicsulfinyl group, a sulfamoyl group and a sulfonic acid group. A hydrogenatom of these substituents may be substituted.

[D] can be one selected from the group including the elements describedbelow: a hydrogen atom, a halogen atom, an aliphatic group, an aromaticgroup, a hydroxyl group, an alkoxy group, an aryloxy group, an acyloxygroup and a heterocyclic oxy group. Furthermore, an amino group, anacylamino group, an arylamino group, a ureido group, a sulfamoylaminogroup, an alkoxycarbonyl amino group, an aryloxycarbonylamino group, analkylthio group, an arylthio group or a heterocyclic thio group can beused. Of them, a hydrogen atom, a halogen atom, an alkyl group, ahydroxyl group, an alkoxy group, an aryloxy group, an acyloxy group, anamino group or acylamino group can be used, and particularly a hydrogenatom, an arylamino group, an acylamino group can be used. Thesesubstituents may further have a substituent.

Furthermore, as R₁ and R₂, elements particularly described below can beused. A hydrogen atom, a halogen atom, an alkyl group, an alkoxycarbonylgroup, a carboxy group, a carbamoyl group, a hydroxyl group, an alkoxygroup and a cyano group can be used. These substituents may further havea substituent. R₁ and R₅ or R₅ and R₆ may be joined to form a 5-memberedring or a 6-membered ring.

In the general formula (I), when [A], R₁, R₂, R₅, R₆ and [D] furtherhave a substituent, the substituent may be selected from those to beselected as R₁ and R₂ that can constitute parts of [D], [B] and [C]previously described.

When a compound of the general formula (I) is soluble in water, thecompound further can have an ionic hydrophilic group on one selectedfrom the group including the positions of [A], R₁, R₂, R₅, R₆ and [D] asa substituent. Specific examples of the ionic hydrophilic group servingas a substituent include a sulfonic acid group, a carboxy group, aphosphono group and a quaternary ammonium group. Of the ionichydrophilic groups above, a carboxy group, a phosphono group or asulfonic acid group can be used, and particularly a carboxy group or asulfonic acid group can be used. The carboxy group, phosphono group andsulfonic acid group may be present in the form of a salt. Furthermore,as the counter ion forming a salt, alkali metal ions such as an ammoniumion, a lithium ion, a sodium ion and a potassium ion and organic cationssuch as a tetramethyl ammonium ion and a tetramethyl guanidinium ion maybe mentioned.

Next, each of the substituents will be more specifically describedbelow. In the present invention, the aliphatic group refers to an alkylgroup, a substituted alkyl group, an alkenyl group, a substitutedalkenyl group, an alkynyl group, a substituted alkynyl group, an aralkylgroup and a substituted aralkyl group. The aliphatic group may have abranch or may have a ring. The number of carbon atoms of the aliphaticgroup can be 1 to 20, and further can be 1 to 16. The aryl moiety of thearalkyl group and substituted aralkyl group can be phenyl or naphthyland particularly phenyl. Specific examples of the aliphatic group caninclude the following groups: a methyl group, an ethyl group, a butylgroup, an isopropyl group, a t-butyl group, a hydroxyethyl group, amethoxyethyl group, a cyanoethyl group, a trifluoromethyl group, a3-sulfopropyl group, a 4-sulfobutyl group, a cyclohexyl group, a benzylgroup, a 2-phenethyl group, a vinyl group and an allyl group.

In the present invention, the aromatic group refers to an aryl group anda substituted aryl group. The aryl group can be phenyl or naphthyl, andparticularly phenyl. The number of carbon atoms of the aromatic groupcan be 6 to 20, and further can be 6 to 16. Specific examples of thearomatic group can include a phenyl group, a p-tolyl group, ap-methoxyphenyl group, an o-chlorophenyl group and am-(3-sulfopropylamino)phenyl group.

As the heterocyclic group, a heterocyclic group having a substituent andan unsubstituted heterocyclic group may be mentioned. The heterocyclicring may be joined with an aliphatic ring, an aromatic ring or otherheterocyclic rings by condensation. As the heterocyclic group,heterocyclic groups of a 5-membered ring or a 6-membered ring can bementioned. Specific examples of the substituent in this case include analiphatic group, a halogen atom, an alkylsulfonyl group, an arylsulfonylgroup, an acyl group, an acylamino group, a sulfamoyl group, a carbamoylgroup and an ionic hydrophilic group. Furthermore, specific examples ofthe heterocyclic group can include a 2-pyridyl group, a 2-thienyl group,a 2-thiazolyl group, a 2-benzothiazolyl group, a 2-benzoxazolyl groupand a 2-furyl group.

As the alkylsulfonyl group or arylsulfonyl group, an alkylsulfonyl grouphaving a substituent or an arylsulfonyl group having a substituent andan unsubstituted alkylsulfonyl group or an unsubstituted arylsulfonylgroup may be mentioned. Specific examples of the alkylsulfonyl group orarylsulfonyl group can include a methylsulfonyl group and aphenylsulfonyl group.

As the alkylsulfinyl group or arylsulfinyl group, an alkylsulfinyl grouphaving a substituent or an arylsulfinyl group having a substituent, anunsubstituted alkylsulfinyl group or an unsubstituted arylsulfinyl groupmay be mentioned. Specific examples of the alkylsulfinyl group orarylsulfinyl group can include a methylsulfinyl group and aphenylsulfinyl group.

As the acyl group, an acyl group having a substituent and anunsubstituted acyl group may be mentioned. As the acyl group, an acylgroup having 1 to 12 carbon atoms can be used. Specific examples of thesubstituent in this case can include an ionic hydrophilic group.Specific examples of the acyl group can include an acetyl group and abenzoyl group.

As the halogen atom, a fluorine atom, a chlorine atom and a bromine atommay be mentioned.

As the amino group, amino groups substituted with an alkyl group, anaryl group and/or a heterocyclic group may be mentioned. The alkylgroup, aryl group and heterocyclic group may further have a substituent.

As the alkylamino group, an alkylamino group having 1 to 6 carbon atomscan be used. Specific examples of the substituent in this case caninclude an ionic hydrophilic group. Specific examples of the alkylaminogroup can include a methylamino group and a diethylamino group. As thearylamino group, an arylamino group having a substituent and anunsubstituted arylamino group may be mentioned. As the arylamino group,an arylamino group having 6 to 12 carbon atoms can be used. Specificexamples of the substituent in this case can include a halogen atom andan ionic hydrophilic group. Specific examples of the arylamino group caninclude a phenylamino group and a 2-chlorophenylamino group.

As the alkoxy group, an alkoxy group having a substituent and anunsubstituted alkoxy group may be mentioned. As the alkoxy group, analkoxy group having 1 to 12 carbon atoms can be used. Specific examplesof the substituent in this case can include an alkoxy group, a hydroxylgroup and an ionic hydrophilic group. Specific examples of the alkoxygroup can include a methoxy group, an ethoxy group, an isopropoxy group,a methoxyethoxy group, a hydroxyethoxy group and a 3-carboxypropoxygroup.

As the aryloxy group, an aryloxy group having a substituent and anunsubstituted aryloxy group may be mentioned. As the aryloxy group, anaryloxy group having 6 to 12 carbon atoms can be used. Specific examplesof the substituent in this case can include an alkoxy group and an ionichydrophilic group. Specific examples of the aryloxy group can include aphenoxy group, p-methoxyphenoxy group and an o-methoxyphenoxy group.

As the acylamino group, an acylamino group having a substituent and anunsubstituted acylamino group may be mentioned. As the acylamino group,an acylamino group having 2 to 12 carbon atoms can be used. Specificexamples of the substituent in this case can include an ionichydrophilic group. Specific examples of the acylamino group can includean acetylamino group, a propionylamino group, a benzoylamino group, anN-phenylacetylamino group and a 3,5-disulfobenzoylamino group.

As the ureido group, a ureido group having a substituent and anunsubstituted ureido group may be mentioned. As the ureido group, aureido group having 1 to 12 carbon atoms can be used. Specific examplesof the substituent in this case can include an alkyl group and an arylgroup. Specific examples of the ureido group can include a3-methylureido group, a 3,3-dimethylureido group and a 3-phenylureidogroup.

As the sulfamoylamino group, a sulfamoylamino group having a substituentand an unsubstituted sulfamoylamino group may be mentioned. Specificexamples of the substituent in this case can include an alkyl group.Specific examples of the sulfamoylamino group can includeN,N-dipropylsulfamoylamino.

As the alkoxycarbonylamino group, an alkoxycarbonylamino group having asubstituent and an unsubstituted alkoxycarbonylamino group may bementioned. As the alkoxycarbonylamino group, an alkoxycarbonylaminogroup having 2 to 12 carbon atoms can be used. Specific examples of thesubstituent in this case can include an ionic hydrophilic group.Specific examples of the alkoxycarbonylamino group can include anethoxycarbonylamino group.

As the alkylsulfonylamino group and arylsulfonylamino group, thefollowing groups may be mentioned which include an alkylsulfonylaminogroup having a substituent and an arylsulfonylamino group having asubstituent, an unsubstituted alkylsulfonylamino group and anunsubstituted arylsulfonylamino group. As the sulfonylamino group, asulfonylamino group having 1 to 12 carbon atoms can be used. Specificexamples of the substituent in this case can include an ionichydrophilic group. Specific examples of the alkylsulfonylamino group andarylsulfonylamino group can include a methylsulfonylamino group, anN-phenylmethylsulfonylamino group, a phenylsulfonylamino group and a3-carboxyphenylsulfonylamino group.

As the carbamoyl group, a carbamoyl group having a substituent and anunsubstituted carbamoyl group may be mentioned. Specific examples of thesubstituent in this case can include an alkyl group. Specific examplesof the carbamoyl group can include a methylcarbamoyl group and adimethylcarbamoyl group.

As the sulfamoyl group, a sulfamoyl group having a substituent and anunsubstituted sulfamoyl group may be mentioned. Specific examples of thesubstituent in this case can include an alkyl group. Specific examplesof the sulfamoyl group can include a dimethylsulfamoyl group and adi-(2-hydroxyethyl)sulfamoyl group.

As the alkoxycarbonyl group, an alkoxycarbonyl group having asubstituent and an unsubstituted alkoxycarbonyl group may be mentioned.As the alkoxycarbonyl group, an alkoxycarbonyl group having 2 to 12carbon atoms can be used. Specific examples of the substituent in thiscase can include an ionic hydrophilic group. Specific examples of thealkoxy carbonyl group can include a methoxycarbonyl group and anethoxycarbonyl group.

As the acyloxy group, an acyloxy group having a substituent and anunsubstituted acyloxy group may be mentioned. As the acyloxy group, anacyloxy group having 1 to 12 carbon atoms can be used. Specific examplesof the substituent in this case can include an ionic hydrophilic group.Specific examples of the acyloxy group can include an acetoxy group anda benzoyloxy group.

As the carbamoyloxy group, a carbamoyloxy group having a substituent andan unsubstituted carbamoyloxy group may be mentioned. Specific examplesof the substituent in this case can include an alkyl group. Specificexamples of the carbamoyloxy group can include an N-methylcarbamoyloxygroup.

As the aryloxycarbonyl group, an aryloxycarbonyl group having asubstituent and an unsubstituted aryloxycarbonyl group may be mentioned.As the aryloxycarbonyl group, an aryloxycarbonyl group having 7 to 12carbon atoms can be used. Specific examples of the substituent in thiscase can include an ionic hydrophilic group. Specific examples of thearyloxycarbonyl group can include a phenoxycarbonyl group.

As the aryloxycarbonylamino group, an aryloxycarbonylamino group havinga substituent and an unsubstituted aryloxycarbonylamino group may bementioned. As the aryloxycarbonylamino group, an aryloxycarbonylaminogroup having 7 to 12 carbon atoms can be used. Specific examples of thesubstituent in this case can include an ionic hydrophilic group.Specific examples of the aryloxycarbonylamino group can include aphenoxycarbonylamino group.

As the alkylthio group, arylthio group and heterocyclic thio group, analkylthio group, arylthio group and heterocyclic thio group having asubstituent and an unsubstituted alkylthio group, arylthio group andheterocyclic thio group may be mentioned. As the alkylthio group,arylthio group and heterocyclic thio group, those having 1 to 12 carbonatoms can be used. Specific examples of the substituent in this case caninclude an ionic hydrophilic group. Specific examples of the alkylthiogroup, arylthio group and heterocyclic thio group can include amethylthio group, a phenylthio group and a 2-pyridylthio group.

As the silyloxy group, a silyloxy group substituted with an aliphaticgroup or aromatic group having 1 to 12 carbon atoms can be used.Specific examples of the silyloxy group can include a trimethylsilyloxygroup and a diphenylmethylsilyloxy group.

As the heterocyclic oxy group, a heterocyclic oxy group having asubstituent and an unsubstituted heterocyclic oxy group may bementioned. As the heterocyclic oxy group, a heterocyclic oxy grouphaving 2 to 12 carbon atoms can be used. Specific examples of thesubstituent in this case can include an alkyl group, an alkoxy group,and an ionic hydroxyl group. Specific examples of the heterocyclic oxygroup can include a 3-pyridyloxy group and a 3-thienyloxy group.

As the alkoxycarbonyloxy group, an alkoxycarbonyloxy group having asubstituent and an unsubstituted alkoxycarbonyloxy group may bementioned. As the alkoxycarbonyloxy group, an alkoxycarbonyl grouphaving 2 to 12 carbon atoms can be used. Specific examples of thealkoxycarbonyloxy group can include a methoxycarbonyloxy group and anisopropoxycarbonyloxy group.

As the aryloxycarbonyloxy group, an aryloxycarbonyloxy group having asubstituent and an unsubstituted aryloxycarbonyloxy group may bementioned. As the aryloxycarbonyloxy group, an aryloxycarbonyloxy grouphaving to 7 to 12 carbon atoms can be used. Specific examples of thearyloxycarbonyloxy group can include a phenoxycarbonyloxy group.

As the heterocyclic oxycarbonyl group, a heterocyclic oxycarbonyl grouphaving a substituent and an unsubstituted heterocyclic oxycarbonyl groupmay be mentioned. As the heterocyclic oxycarbonyl group, a heterocyclicoxycarbonyl group having 2 to 12 carbon atoms can be used. Specificexamples of the substituent in this case can include an ionichydrophilic group. Specific examples of the heterocyclic oxycarbonylgroup can include a 2-pyridyloxycarbonyl group.

As the heterocyclic sulfonylamino group, a heterocyclic sulfonylaminogroup having a substituent and an unsubstituted heterocyclicsulfonylamino group may be mentioned. As the heterocyclic sulfonylaminogroup, a heterocyclic sulfonylamino group having 1 to 12 carbon atomscan be used. Specific examples of the substituent in this case caninclude an ionic hydrophilic group. Specific examples of theheterocyclic sulfonylamino group can include a 2-thiophenesulfonylaminogroup and a 3-pyridinesulfonylamino group.

As the heterocyclic sulfonyl group, a heterocyclic sulfonyl group havinga substituent and an unsubstituted heterocyclic sulfonyl group may bementioned. As the heterocyclic sulfonyl group, a heterocyclic sulfonylgroup having 1 to 12 carbon atoms can be used. Specific examples of thesubstituent in this case can include an ionic hydrophilic group.Specific examples of the heterocyclic sulfonyl group can include a2-thiophenesulfonyl group and a 3-pyridinesulfonyl group.

As the heterocyclic sulfinyl group, a heterocyclic sulfinyl group havinga substituent and an unsubstituted heterocyclic sulfinyl group may bementioned. As the heterocyclic sulfinyl group, a heterocyclic sulfinylgroup having 1 to 12 carbon atoms can be used. Specific examples of theheterocyclic sulfinyl group can include a 4-pyridinesulfinyl group.

In the present invention, a compound of the general formula (I) can be acompound represented by the following general formula (I-2)(hereinafter, sometimes referred to as a “compound of the generalformula (I-2)).

wherein, Z₁ is an electron withdrawing group having a Hammett σp valueof 0.20 or more; Z₂ is a hydrogen atom, an aliphatic group, an aromaticgroup or a heterocyclic group; R₁, and R₂ are each independently ahydrogen atom or a substituent selected from the group described below.The group of substituents includes a halogen atom, an aliphatic group,an aromatic group, a heterocyclic group, a cyano group, a carboxy group,a carbamoyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, aheterocyclic oxycarbonyl group, an acyl group, a hydroxyl group, analkoxy group, an aryloxy group, a heterocyclic oxy group, an silyloxygroup, an acyloxy group, a carbamoyloxy group, an alkoxycarbonyloxygroup, an aryloxycarbonyloxy group, an amino group, an acylamino group,a ureido group, a sulfamoylamino group, an alkoxycarbonylamino group, anaryloxycarbonylamino group, an alkylsulfonylamino group, anarylsulfonylamino group, a heterocyclic sulfonylamino group, a nitrogroup, an alkylthio group, an arylthio group, a heterocyclic thio group,an alkylsulfonyl group, an arylsulfonyl group, a heterocyclic sulfonylgroup, an alkylsulfinyl group, an arylsulfinyl group, a heterocyclicsulfinyl group, a sulfamoyl group and a sulfonic acid group. A hydrogenatom of these substituents may be substituted. R₃ and R₄ are eachindependently one selected from the group including a hydrogen atom, analiphatic group, an aromatic group, a heterocyclic group, an acyl group,an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, analkylsulfonyl group, an arylsulfonyl group and a sulfamoyl group. R₅ andR₆ are each independently a hydrogen atom or a substituent selected fromthe group described below. The group of substituents includes analiphatic group, an aromatic group, a heterocyclic group, an acyl group,an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, analkylsulfonyl group, an arylsulfonyl group and a sulfamoyl group. Ahydrogen atom of these substituents may be substituted. [G] of theformula is one selected from the group including a hydrogen atom, analiphatic group, an aromatic group and a heterocyclic group.

In the general formula (I-2), Z₁ is an electron withdrawing group havinga Hammett up value of 0.20 or more. Z₁ is an electron withdrawing grouphaving a Hammett σp value of 0.20 or more; however, in the presentinvention, a Hammett σp value can be 0.30 or more, further can be 0.45or more, and particularly can be 0.60 or more. On the other hand, aHammett up value can be below 1.0.

Regarding Z₁ herein, Hammett rule and a Hammett substituent constant σpvalue (hereinafter, referred to as “Hammett σp value”) will bedescribed. The Hammett rule is an empirical rule proposed by L. P.Hammett in 1935 to quantitatively discuss the effect of a substituent onthe reaction and equilibrium of a benzene derivative and nowadaysvalidity thereof is widely recognized. The substituent constantsobtained by the Hammett rule are σp value and σm value, which aredescribed in many general publications. Detailed descriptions are foundin, for example, Lange s Handbook of Chemistry, the 12th edition, editedby J. A. Dean, 1979, McGraw-Hill and Region of Chemistry, extra number,122, page 96 to 103, 1979, Nankodo.

Note that, in the present invention, a substituent Z₁ of the generalformula (I-2) is defined on the basis of Hammett σp value; however, thepresent invention is not limited only to the substituent whose σp valueis specifically described in the aforementioned publications. Needlessto say, a substituent whose σp value is not specifically described inthe aforementioned publications but will be within the range ifcalculated on the basis of the Hammett rule, is included in the presentinvention. Compounds of the general formula (I) and compounds of thegeneral formula (I-2) include a compound other than benzene derivatives;however, in the present invention, a σp value is used as a standardindicating the effect of electrons of a substituent irrelevant to thesubstitution position. Specific examples of the substituents that can beused as an electron withdrawing group having a Hammett σp value of 0.20or more of the compounds of the general formula (I) or the compounds ofthe general formula (I-2) will be described below, separately by therange of Hammett σp value.

Electron withdrawing groups having a Hammett σp value of 0.60 or moreare as follows: a cyano group, a nitro group, an alkylsulfonyl group(e.g., arylsulfonyl groups such as a methanesulfonyl group and abenzenesulfonyl group).

Electron withdrawing groups having a Hammett σp value of 0.45 or moreinclude the following groups in addition to the aforementioned ones: anacyl group (e.g., an acetyl group), an alkoxycarbonyl group (e.g., adodecyloxycarbonyl group), an aryloxycarbonyl group (e.g., am-chlorophenoxycarbonyl group), an alkylsulfinyl group (e.g., an-propylsulfinyl group), an arylsulfinyl group (e.g., a phenylsulfinylgroup), a sulfamoyl group (e.g., an N-ethylsulfamoyl group, anN,N-dimethylsulfamoyl group) and a halogenated alkyl group (e.g., atrifluoromethyl group).

Electron withdrawing groups having a Hammett σp value of 0.30 or moreinclude the following groups in addition to the aforementioned ones: anacyloxy group (e.g., an acetoxy group), a carbamoyl group (e.g., anN-ethylcarbamoyl group and an N,N-dibutylcarbamoyl group), a halogenatedalkoxy group (e.g., a trifluoromethyloxy group), a halogenated aryloxygroup (e.g., a pentafluorophenyloxy group), a sulfonyloxy group (e.g., amethylsulfonyloxy group), a halogenated alkylthio group (e.g., adifluoromethylthio group), an aryl group substituted by 2 or moreelectron withdrawing groups having a σp value of 0.15 or more (e.g., a2,4-dinitrophenyl group and a pentachlorophenyl group) and aheterocyclic group (e.g., a 2-benzoxazolyl group, a 2-benzothiazolylgroup and a 1-phenyl-2-benzimidazolyl group).

Electron withdrawing groups having a Hammett σp value of 0.20 or moreinclude the following groups in addition to the aforementioned ones: ahalogen atom (e.g., fluorine, chlorine, bromine).

In the compound to be used in the present invention, Z₁ of the generalformula (I-2) can be any one of the groups described below: an acylgroup having 2 to 12 carbon atoms, an alkyloxycarbonyl group having 2 to12 carbon atoms, a nitro group, a cyano group, an alkylsulfonyl grouphaving 1 to 12 carbon atoms, an arylsulfonyl group having 6 to 18 carbonatoms, a carbamoyl group having 1 to 12 carbon atoms, or a halogenatedalkyl group having 1 to 12 carbon atoms. Furthermore, a cyano group, analkylsulfonyl group having 1 to 12 carbon atoms, or an arylsulfonylgroup having 6 to 18 carbon atoms can be further used, and particularlya cyano group can be used.

In the general formula (I-2) previously described, R₁, R₂, R₅ and R₆ arethe same as defined in the general formula (I). In the general formula(I-2), R₃ and R₄ are each independently selected from the group below:any one of a hydrogen atom, an aliphatic group, an aromatic group, aheterocyclic group, an acyl group, an alkoxycarbonyl group, anaryloxycarbonyl group, a carbamoyl group, an alkylsulfonyl group, anarylsulfonyl group and a sulfamoyl group. Of them, a hydrogen atom, anaromatic group, a heterocyclic group, an acyl group, an alkylsulfonylgroup or an arylsulfonyl group can be used, and further a hydrogen atom,an aromatic group or a heterocyclic group can be used. Furthermore, inthe general formula (I-2), Z₂ is one selected from the group including ahydrogen atom, an aliphatic group, an aromatic group and a heterocyclicgroup.

In the general formula (I-2) previously described, [G] is one selectedfrom the group including a hydrogen atom, an aliphatic group, anaromatic group and a heterocyclic group. Of them, a group havingnon-metal atoms required for forming a 5-membered ring to a 8-memberedring can be used. These 5-membered ring to 8-membered ring may besubstituted or a saturated ring, or may have an unsaturated bond. Ofthem, particularly, an aromatic group or a heterocyclic group can beused. As the non-metal atoms, a nitrogen atom, an oxygen atom, a sulfuratom and a carbon atom may be mentioned. Specific examples of the ringstructure include the following rings: a benzene ring, a cyclopentanering, a cyclohexane ring, a cycloheptane ring, a cyclooctane ring, acyclohexene ring, a pyridine ring, a pyrimidine ring, a pyrazine ring, apyridazine ring, a triazine ring, an imidazole ring, a benzimidazolering, an oxazole ring, a benzoxazole ring, a thiazole ring, abenzothiazole ring, an oxane ring, a sulfolane ring and a thiane ring.

Each of the substituents constituting a compound of the general formula(I-2) may further have a substituent. As the substituent in the casewhere each of the substituents further has a substituent, thesubstituents exemplified in the general formula (I), the substituentsexemplified as [D] or R₁ and R₂ constituting the general formula (I) andan ionic hydrophilic group may be mentioned.

Next, in the present invention, a particularly desirable structure of acompound of the general formula (I) previously described will bedescribed below. First, the combination of R₅ and R₆ of a compound ofthe general formula (I) can be one particularly selected from the groupincluding the following groups. More specifically, the combination of R₅and R₆ can be one selected from the group including a hydrogen atom, analkyl group, an aryl group, a heterocyclic group, a sulfonyl group andan acyl group. Furthermore, the combination of R₅ and R₆ can be oneselected from the group including a hydrogen atom, an aryl group, aheterocyclic group and a sulfonyl group. Particularly, the combinationof R₅ and R₆ can be one selected from the group including a hydrogenatom, an aryl group and a heterocyclic group. However, R₅ and R₆ may notsimultaneously take a hydrogen atom.

Furthermore, in the present invention, [D] of a compound of the generalformula (I) can be any one of the following groups. Specifically, ahydrogen atom, a halogen atom, an aliphatic group, an aromatic group, ahydroxyl group, an alkoxy group, an aryloxy group, an acyloxy group, aheterocyclic oxy group, an amino group, an acylamino group, an arylaminogroup, a ureido group, a sulfamoylamino group, an alkoxycarbonyl aminogroup, an aryloxycarbonylamino group, an alkylthio group, an arylthiogroup or a heterocyclic thio group can be mentioned. Furthermore, ahydrogen atom, a halogen atom, an alkyl group, a hydroxyl group, analkoxy group, an aryloxy group, an acyloxy group, an amino group or anacylamino group can be mentioned. Particularly, a hydrogen atom, anarylamino group or an acylamino group can be mentioned. Thesesubstituents may further have a substituent.

Furthermore, in the present invention, [A] of a compound of the generalformula (I) can be any one of the following groups. Specifically, apyrazole ring, an imidazole ring, an isothiazole ring, a thiadiazolering or a benzothiazole ring can be mentioned. Furthermore, a pyrazolering or an isothiazole ring can be mentioned. Particularly, a pyrazolering can be mentioned.

Furthermore, in the present invention, [B] and [C] of a compound of thegeneral formula (I) can be CR₁ and CR₂, respectively. Furthermore, R₁and R₂ can be each independently a hydrogen atom, a halogen atom, acyano group, a carbamoyl group, a carboxy group, an alkyl group, ahydroxyl group, an alkoxy group or an alkoxycarbonyl group, andparticularly, a hydrogen atom, an alkyl group, a carboxy group, a cyanogroup or a carbamoyl group.

Note that, in the desirable combination of substituents constituting acompound of the general formula (I) that can be used, at least one ofthe substituents can be a group as mentioned above. A larger number ofsubstituents can be groups as mentioned above. Particularly, allsubstituents can be groups as mentioned above.

As a specific example of a compound of the general formula (I) or acompound of the general formula (I-2), the following compounds I-1 toI-44 exemplified below may be mentioned. As a matter of course, thepresent invention is not limited to the compounds thus exemplified. Anycompound may be used as long as the structure and definition of thecompound fall within the range of those of the general formula (I) orthe general formula (I-2).

Dye R₂₁ I-1

I-2

I-3

I-4

I-5

Dye R₂₂ R₂₃ I-1

I-2

I-3

I-4

I-5

Dye R₂₄ R₂₅ R₂₆ R₂₇ I-6

I-7

I-8

I-9

I-10

Dye R₂₈ I-11

I-12

I-13

I-14

I-15

Dye R₂₉ I-11

I-12

I-13

I-14

I-15

Dye R₃₀ R₃₁ I-11

I-12

I-13

I-14

I-15

Dye R₃₂ R₃₃ I-16

I-17

I-18

I-19

Dye R₃₄ R₃₅ I-16

I-17

I-18

I-19

Dye R₃₆ R₃₇ R₃₈ I-20

—CN

I-21

—Br

I-22

—SO₂CH₃

I-23

—CN

I-24

—Br

I-25

—CN

I-26

—CN

Dye R₃₉ R₄₀ R₄₁ R₄₂ R₄₃ I-20 —H —CONH₂ —SO₂CH₃

I-21 —COOEt —H

—C₈H₁₇(t) —COCH₃ I-22 —CONH₂ —H

I-23 —H —H

—SO₂CH₃ I-24 —H —CONH₂

I-25 —CH₃ —H

I-26 —CH₃ —CN —H

Dye R₄₄ R₄₅ R₄₆ R₄₇ R₄₈ R₄₉ I-27 —CH₃ —CH₃ —CN —H

I-28 —CH₃ —CH₃ —CN —H

I-29 —CH₃ —CH₃ —CONH₂ —H

I-30 —CH₃ —CH₃ —H —H

I-31 —CH₃ —H —CN —H

I-32 —CH₃ —CH₃ —H

I-33 —CH₃ —CH₃ —H

I-34 —CH₃ —H —H —SO₂CH₃

Dye R₅₀ R₅₁ R₅₂ I-35 —SCH₃ —CH₃ —CN I-36

—H —CONH₂ I-37

—CH₃ —H I-38 —CH₃ —CH₃ —H I-39

—H —H Dye R₅₃ R₅₄ R₅₅ I-35 —H —C₈H₁₇(t)

I-36 —H

I-37

I-38

I-39

—C₈H₁₇(t)

Dye R₅₆ R₅₇ R₅₈ I-40 5-Cl —CH₃ —CONH₂ I-41 5,6-diCl —H —H I-42 5,6-diCl—CH₃ —H I-43 5-CH₃ —H —CN I-44 5-NO₂ —CH₃ —H Dye R₅₉ R₆₀ R₆₁ I-40 —H—C₈H₁₇(t) —C₈H₁₇(t) I-41

I-42

—COCH₃ I-43 —H

I-44 —SO₂CH₃

In the present invention, a compound of the general formula (I) can beparticularly a compound represented by the following general formula(I-3) (hereinafter, sometimes referred to as a “compound of the generalformula (I-3)”).

wherein, R₆₂, R₆₃, R₆₄ and R₆₅ are each independently an alkyl group;M(s) are each independently one selected from the group including ahydrogen atom, an alkali metal, ammonium and organic ammonium.

In the general formula (I-3), R₆₂, R₆₃, R₆₄ and R₆₅ are eachindependently an alkyl group. The alkyl group can have 1 to 3 carbonatoms in view of solubility to an aqueous medium constituting ink.Specifically, a methyl group, an ethyl group, a primary propyl group anda secondary propyl group may be mentioned. Note that if the alkyl grouphas 4 or more carbon atoms, a coloring material has large hydrophobicityand thus may not be always dissolved in an aqueous medium constitutingink.

In the general formula (I-3), M(s) are each independently one selectedfrom the group including an alkali metal, ammonium and organic ammonium.As the alkali metal, for example, lithium, sodium and potassium may bementioned. As the organic ammonium, for example, acetamide, benzamide,methylamino, butylamino, diethylamino, phenylamino and triethanolaminomay be mentioned.

As specific examples of a compound of the general formula (I-3), thecompounds I-45 to I-47. exemplified below can be mentioned. Note thatthe compounds exemplified below will be expressed in the form of freeacid. As a matter of course, the present invention is not limited to thefollowing compounds exemplified below. Any compound may be used as longas the structure and definition of the compound fall within those of thegeneral formula (I-3). Of the compounds exemplified below, the compoundI-46 can be particularly used herein.

(Compound Represented by the General Formula (II))

As described above, the present inventors conducted various studies onformulation of ink in order to further improve the lightfastness of animage recorded by ink containing a compound of the general formula (I)above. To be more specifically, studies have been made to improve thefastness properties of an image recorded by ink containing a compound ofthe general formula (I) by using compounds, which are conventionallyknown to improve the fastness properties of an image. However, it wasfound that use of such a compound in combination with a compound of thegeneral formula (I) raises another problem such as deterioration ofsticking resistance of ink and insufficient intermittent ejectionstability.

Then, the present inventors studied on a wide variety of materialsincluding various types of water-soluble organic solvents and compoundsas a compound to be used in combination with a compound of the generalformula (I) above. As a result, they found that addition of a compoundof the following general formula (II) to the ink containing a compoundof the general formula (I) above can drastically improve thelightfastness of an image recorded by the ink. Furthermore, use of acompound of the following general formula (II) improves the stickingresistance of ink and intermittent ejection stability, and maintainsreliability of ink and the lightfastness of an image simultaneously athigh levels.

R_(x)-[E]-R_(y)   General formula (II)

wherein, in general formula (II), -[E]- is —S—, —S(═O)— or —S(═O)₂—;R_(x) and R_(y) are each independently one selected from the groupincluding a hydrogen atom, a hydroxyl group, an alkyl group, ahydroxyalkyl group, an alkenyl group, an acyl group, a carbamoyl group,a carboxy group and a sulfonyl group, with the proviso that R_(x) andR_(y) may not simultaneously take hydrogen atoms or hydroxyl groups oran hydrogen atom and a hydroxyl group.

In the general formula (II), R_(x) and R_(y) are each independently oneselected from the group including a hydrogen atom, a hydroxyl group, analkyl group, a hydroxyalkyl group, an alkenyl group, an acyl group, acarbamoyl group, a carboxy group and a sulfonyl group. As the alkylgroup, an alkyl group having 1 to 4 carbon atoms can be used. Morespecifically, for example, a methyl group, an ethyl group, a n-propylgroup, an iso-propyl group, a n-butyl group, a sec-butyl group, at-butyl group and an iso-butyl group may be mentioned. As thehydroxyalkyl group, for example, a hydroxymethyl group, a hydroxyethylgroup, a hydroxypropyl group and a hydroxybutyl group may be mentioned.As the acyl group, for example, an acetyl group and a benzoyl group maybe mentioned. As the carbamoyl group, for example, a methylcarbamoylgroup and a dimethylcarbamoyl group may be mentioned.

In the present invention, in the general formula (II) above, there is adescription reading “R_(x) and R_(y) may not simultaneously takehydrogen atoms or hydroxyl groups or an hydrogen atom and a hydroxylgroup”. This phrase means that, in the general formula (II), a casewhere R_(x) and R_(y) simultaneously take a hydrogen atom, a case whereR_(x) and R_(y) simultaneously take a hydroxyl group and a case whereone of R_(x) and R_(y) is a hydrogen atom and the other one is ahydroxyl group are not included.

The mechanism of improving the lightfastness of an image recorded by theink containing a compound of the general formula (I) and a compound ofthe general formula (I) is not specifically elucidated; however, thepresent inventors predict the reason as follows. A compound of thegeneral formula (I) has a strong electron withdrawing group. Therefore,on the recording medium to which ink is applied, a polar group of acompound of the general formula (II), specifically, a substituent for asulfur atom, is selectively adsorbed onto a compound of the generalformula (I) at a site having a low electron density, thereby protectingthe compound of the general formula (I). As a result, decomposition ofthe compound of the general formula (I) by light, i.e. UV energy, issuppressed and the lightfastness of the image conceivably improves.

Examples of a compound of the general formula (II) above that can beused include sulfin, sulfinic acid, dimethylsulfin, dimethylsulfoxide,dimethylsulfone, (2-hydroxyethyl)methylsulfone, thiodiglycol,bis(2-hydroxyethyl)sulfoxide, 1-(2-hydroxyethylthio)-2-propanol andbis(2-hydroxyethyl)sulfone. Note that the present invention is notlimited to the compounds described above. Any compound may be used aslong as the structure of the compound is included in the structure ofthe general formula (II). Of the compounds exemplified above,particularly, bis(2-hydroxyethyl)sulfone can be used herein.

The content (% by mass) of a compound of the general formula (II) in inkcan be 1.0% by mass or more to 30.0% by mass or less with respect to thetotal mass of the ink. If the content of a compound of the generalformula (II) is less than 1.0% by mass, the effect of improving thelightfastness of an image may not sometimes be sufficiently obtained. Onthe other hand, if the content of a compound of the general formula (II)exceeds 30.0% by mass, intermittent ejection stability may not besufficiently obtained.

(Glycerin)

The present inventors further conducted studies in order tosimultaneously attain the lightfastness of an image recorded by the inkcontaining a compound of the general formula (I) above and thereliability of the ink at higher levels. As a result, they found thatuse of glycerin as a compound to be used in combination with thecompound of the general formula (I) in addition to a compound of thegeneral formula (II) can attain these performances at higher levels andfurther improves recovery from the state of sticking. To describe morespecifically, when glycerin is used in combination, it is desirable thatthe content of glycerin (% by mass) in ink is set at 1.0% by mass ormore to 20.0% by mass or less with respect to the total mass of the ink.If the content of glycerin is less than 1.0% by mass, the effect ofimproving sticking resistance may not be always sufficiently obtained.On the other hand, if the content of glycerin exceeds 20.0% by mass, theeffect of improving intermittent ejection stability may not be alwayssufficiently obtained.

Furthermore, the present inventors found that when a compound of thegeneral formula (II) and glycerin were used in combination with acompound of the general formula (I), the sum of the contents of thecompound of the general formula (II) and glycerin can fall within therange below. To be more specific, if the content is prepared asdescribed below, the lightfastness of an image and sticking resistanceof ink can be simultaneously obtained at high levels. In addition,intermittent ejection stability can be improved. More specifically, itis desirable that the sum of the content of the compound of the generalformula (II) (% by mass) and the content of glycerin (% by mass) is 8.0%by mass or more to 23.0% by mass or less with respect to the total massof the ink. On the contrary, if the sum of the contents of the compoundsdoes not fall within the aforementioned range, the effect of improvingintermittent ejection stability may not be always sufficiently obtained.

Furthermore, the present inventors found that an additional effect canbe obtained by controlling the mass ratio of the content of a compoundof the general formula (II) and the content of glycerin in ink to fallwithin a predetermined range. That is, if the control is made in thisway, sticking resistance and intermittent ejection stability are furtherimproved. Furthermore, when such ink was applied to an ink jet recordingsystem, in which ink is ejected by the action of thermal energy, thewire breakage of a heater of a recording head was found to be moreeffectively suppressed. More specifically, it is sufficient that themass ratio of the content (% by mass) of a compound of the generalformula (II) to the content (mass) of glycerin with respect to the totalmass of ink, in other words, a value of (the content of a compound ofthe general formula (II)/the content of glycerin) is set at 0.40 or moreto 5.90 or less. In contrast, if the mass ratio is less than 0.40, theeffect of improving sticking resistance and intermittent ejectionstability may not be always sufficiently obtained. On the other hand, ifthe mass ratio exceeds 5.90, when such ink is applied to an ink jetrecording system, in which ink is ejected by the action of thermalenergy, and electric pulse is applied predetermined times, the wire of aheater of a recording head is sometimes broken. In short, recordingdurability may sometimes decrease.

(Compound Represented by the General Formula (III))

The ink of the present invention contains a compound of the generalformula (I) previously described as a coloring material. According tothe studies conducted by the present inventors, use of this coloringmaterial in combination with a compound described below can provide animage having a more desirable color tone as magenta ink. Specifically,use of a compound represented by the following general formula (III),which is an anthrapyridone dye, in a predetermined mass ratio asdescribed below can provide an image having a more desirable color toneas magenta ink.

wherein, R_(z)(s) are each independently a hydrogen atom, an alkylgroup, a hydroxyalkyl group, a cyclohexyl group, a monoalkylaminoalkylgroup or dialkylaminoalkyl group. M(s) are each independently oneselected from the group including a hydrogen atom, an alkali metal,ammonium and organic ammonium. [F] is a linking group.

In the general formula (III), R_(z)(s) are each independently a hydrogenatom, an alkyl group, a hydroxyalkyl group, a cyclohexyl group, amonoalkylaminoalkyl group or dialkylaminoalkyl group.

As the alkyl group, an alkyl group having 1 to 8 carbon atoms may bementioned. Specifically, for example, a methyl group, an ethyl group, an-propyl group, an iso-propyl group, a n-butyl group, a sec-butyl group,a t-butyl group, an iso-butyl group, a n-pentyl group, a n-hexyl group,a n-heptyl group and a n-octyl group may be mentioned.

As the hydroxyalkyl group, a hydroxyalkyl group having 1 to 4 carbonatoms may be mentioned. Specifically, a hydroxymethyl group, ahydroxyethyl group, a hydroxypropyl group and a hydroxybutyl group maybe mentioned. As the alkyl of the hydroxyalkyl group, straight-chain,branched and cyclic alkyl may be mentioned; however, a straight-chainalkyl can be particularly used. Furthermore, alkyl may be substitutedwith hydroxy at any position; however, an alkyl substituted with hydroxyat an end, for example, a 2-hydroxyethyl group, a 3-hydroxypropyl groupand a 4-hydroxybutyl group can be particularly used.

As the monoalkylaminoalkyl group, a mono-C1 to C4 alkylamino-C1 to C4alkyl group may be mentioned. Specifically, for example, amonomethylaminopropyl group and a monoethylaminopropyl group may bementioned.

As the dialkylaminoalkyl group, a di-C1 to C4 alkylamino-C1 to C4 alkylgroup may be mentioned. Specifically, for example, a dimethylaminopropylgroup and a diethylaminoethyl group may be mentioned.

In the present invention, R_(z)(s) can be a hydrogen atom, an alkylgroup or a cyclohexyl group, further can be a hydrogen atom or an alkylgroup, and particularly can be a methyl group.

As the general formula (III), [F] is a linking group. As the linkinggroup, for example, the following linking groups 1 to 7 may bementioned. In linking groups 1 to 7, a bond marked with “*” is a bond ofeach of the nitrogen atoms. Nitrogen atoms are directly bonded to twodifferent triazine rings, respectively. Of the linking groups, linkinggroup 1 can be particularly used.

wherein, n is 2 to 8, can be 2 to 6 and further can be 2; and marks “*”are binding sites to two different 2 triazine rings.

wherein, R_(a)(s) are each independently a hydrogen atom or a methylgroup; and marks “*” are binding sites to two different 2 triazinerings.

wherein, marks “*” are binding sites to two different 2 triazine rings.

wherein, marks “*” are binding sites to two different 2 triazine rings.

wherein, marks “*” are binding sites to two different 2 triazine rings.

wherein, m is 2 to 4, marks “*” are binding sites to two different 2triazine rings.

wherein, marks “*” are binding sites to two different 2 triazine rings.

In the general formula (III), M(s) are each independently one selectedfrom the group including a hydrogen atom, an alkali metal, ammonium andorganic ammonium. As the alkali metal, for example, lithium, sodium andpotassium may be mentioned. As the organic ammonium, for example,acetamide, benzamide, methylamino, butylamino, diethylamino,triethanolamino and phenylamino may be mentioned.

In the general formula (III), the alkyl group can have 1 to 3 carbonatoms in view of solubility to an aqueous medium constituting ink, andspecifically a methyl group, an ethyl group, a primary propyl group anda secondary propyl group may be mentioned. Note that, when the number ofcarbon atoms of the alkyl group is 4 or more, the hydrophobicity of acoloring material increases, the coloring material may not be alwaysdissolved in the aqueous medium constituting ink.

Specific examples of a compound represented by the general formula (III)that can be used include compounds III-1 and III-2 exemplified below.Note that, the compounds exemplified below are expressed in the form offree acid. As a matter of course, the present invention is not limitedto the following compounds. Any compound may be used as long as thestructure and definition of the compound fall within the range of thoseof the general formula (III). In the present invention, particularly, acompound III-1 of the exemplified compounds can be used.

(Color Tone of Ink)

A compound of the general formula (I) has yellowish magenta color toneand characterized in that the compound provides an image having highoptical density. On the other hand, a compound of the general formula(III) has bluish magenta color tone and characterized in that thecompound provides an image having a low optical density. In the presentinvention, use of a compound of the general formula (I) and a compoundof the general formula (III) having the aforementioned characteristicsin a predetermined mass ratio can provide the magenta color tone thatcan be used.

The ink of the present invention has magenta color tone. Morespecifically, the color tone of magenta ink that can be used in thepresent invention is as follows. With respect to an image recorded byuse of ink with a recording duty of 100%, a* and b* of the L*a*b*display system defined by the CIE (Commission Internationale del'Eclairage (International Commission on Illumination)) are measured. Onthe basis of the obtained a* and b* values and the following equation(A), hue angle (H°) is calculated. Ink having a hue angle of 0 or moreto 5 or less, or 350 or more to 360 or less is defined as ink having thecolor tone that can be particularly used as magenta ink in the presentinvention. Furthermore, the hue angle (H°) calculated on the basis ofthe following equation (A) can be particularly 0 or more to 5 or less.Note that the a* and b* values can be measured, for example, byspectrophotometer (trade name: Spectrolino; manufactured by GretagMacbeth). As a matter of course, the present invention is not limited tothis.

In a*≧0, b*≧0 (first quadrant), H°=tan⁻¹(b*/a*)

In a*≦0, b*≧0 (second quadrant), H°=180+tan⁻¹(b*/a*)

In a*≦0, b*≦0 (third quadrant), H°=180+tan⁻¹(b*/a*)

In a*≧0, b*≦0 (fourth quadrant), H°=360+tan⁻¹(b*/a*)   Equation (A)

(Content of Coloring Material)

In the present invention, the content (% by mass) of a compound of thegeneral formula (I) in ink can be 0.1% by mass or more to 10.0% by massor less with respect to the total mass of the ink, and further can be0.5% by mass or more to 2.0% by mass or less. Furthermore, as describedabove, when a compound of the general formula (I) and a compound of thegeneral formula (III) are used in combination as a coloring material,more excellent results can be obtained. For this, the sum of thecontents (% by mass) of these compounds can fall within the range of4.0% by mass or more to 10.0% by mass or less with respect to the totalmass of the ink. In contrast, when the sum of the contents of colormaterials in ink is less than 4.0% by mass, a sufficient density of animage may not be always obtained. On the other hand, when the sumexceeds 15.0% by mass, sticking resistance may not be alwayssufficiently obtained. Note that, the content (% by mass) of a compoundof the general formula (III) in ink is desirably 2.5% by mass or more to10.0% by mass or less with respect to the total mass of the ink.

Furthermore, when a compound of the general formula (I) and a compoundof the general formula (III) are used in combination as a colormaterial, in order to obtain ink providing an image having the colortone that can be particularly used as magenta ink, as described above,the mass ratio of these compounds is desirably set at as follows: thecontent (% by mass) of a compound of the general formula (III) to thecontent (% by mass) of a compound of the general formula (I) withrespect to the total mass of ink, can be 2.5 or more to 10.0 or lessi.e., {(the content of a compound of the general formula (III)/(thecontent of a compound of the general formula (I))}=2.5 or more to 10.0or less.

(Verification Method of Coloring Material)

To verify whether the coloring material to be used in the presentinvention is contained in ink or not, verification methods (1) to (3)below using high performance liquid chromatography (HPLC) can beapplied.

-   (1) Peak retention time-   (2) Maximum absorption wavelength of the peak (1)-   (3) M/Z(posi) and M/Z(nega) of mass spectrum of the peak (1)

The analysis conditions of high performance liquid chromatography are asshown below. First, diluted liquid (ink) with pure water to about 1,000folds was prepared as a sample to be subjected to measurement. Analysiswas performed by high performance liquid chromatography in the followingconditions and peak retention time and the maximum absorption wavelengthof the peak were measured.

-   Column: SunFire C₁₈(manufactured by Japan Waters), 2.1 mm×150 mm,    column temperature: 40° C.-   Flow rate: 0.2 mL/min-   PDA: 200 nm to 700 nm-   Mobile phase and gradient conditions: Table 1

TABLE 1 Mobile phase and gradient conditions 0-5 5-24 24-31 31-45minutes minutes minutes minutes A: Water 85% 85%→45% 45%→0%  0% B:Methanol 10% 10%→50% 50%→95% 95% C: 0.2 mol/L 5% 5% 5% 5% aqueousammonium acetate solution

Furthermore, mass spectrum analysis conditions are as shown below. Withrespect to the obtained peak, a mass spectrum thereof is measured in thefollowing conditions and values of the M/Z (posi) and M/Z (nega) mostintensively detected are obtained, respectively.

-   Ionization method-   ESI-   Capillary: 3.5 kV-   Solvent-removing gas: 300° C.-   Ion-source temperature: 120° C.-   Detector-   posi: 40 V 200 to 1500 amu/0.9 sec-   nega: 40 V 200 to 1500 amu/0.9 sec

Using the aforementioned method and under the aforementioned conditions,representative examples of individual coloring materials, that is, acompound I-46, which is a specific example of the compound of thegeneral formula (I), and a compound III-1, which is a specific exampleof the compound of the general formula (III), were measured. As aresult, the retention time, maximum absorption wavelength, M/Z (posi)and M/Z (nega) values as shown in Table 2 were obtained. This means thatwhen unknown ink is measured by the same method and under the sameconditions as above and the analysis results correspond to those shownin Table 2, the unknown ink is determined as ink containing a compoundcorresponding to the compound defined in the present invention.

TABLE 2 Analysis results Maximum Retention absorption time wavelengthM/Z [minutes] [nm] posi nega Compound 34.0-35.0 545-565 1176-11791174-1177 I-46 35.0-36.0 545-565 1176-1179 1174-1177 Compound 18.0-19.0500-520 990-993 987-990 III-1

(Aqueous Medium)

Ink of the present invention can employ water or an aqueous medium,which is a solvent mixture of water and a water-soluble organic solvent.As water, deionized water (ion exchange water) can be used. The content(% by mass) of water in ink can be 10.0% by mass or more to 90.0% bymass or less with respect to the total mass of the ink.

The water-soluble organic solvent is not particularly limited as long asit is soluble in water, and an alcohol, a polyhydric alcohol, apolyglycol, glycol ether, a nitrogen-containing polar solvent and asulfur-containing polar solvent and the like may be used. The content (%by mass) of the water-soluble organic solvent in ink can be 5.0% by massor more to 90.0% by mass or less with respect to the total mass of theink, and further can be 10.0% by mass or more to 50.0% by mass or less.When the water-soluble organic solvent is less than the aforementionedrange, reliability such as ejection stability of ink may not be alwaysobtained when the ink is used in an ink jet recording apparatus. On theother hand, when the content of the water-soluble organic solvent ismore than the aforementioned range, the viscosity of the ink increases,with the result that failure of ink supply may sometimes occur. Notethat, the content of the water-soluble organic solvent includes thecontents of a compound of the general formula (II) and glycerin.

Specific examples of the water-soluble organic solvent include thefollowings; C1 to C4 alkyl alcohols such as methyl alcohol, ethylalcohol, n-propyl alcohol, iso-propyl alcohol, n-butyl alcohol,sec-butyl alcohol and tert-butyl alcohol; amides such as dimethylformaldehyde and dimethyl acetamide; ketones or ketone alcohols such asacetone and diacetone alcohol; ethers such as tetrahydrofuran anddioxane; polyalkylene glycols having weight average molecular weight of200 to 1,000 such as polyethylene glycol and polypropylene glycol;glycols such as ethylene glycol, propylene glycol, butylene glycol,diethylene glycol, triethylene glycol and hexylene glycol; alkyleneglycols having an alkylene group with 2 to 6 carbon atoms such as1,5-pentanediol, 1,6-hexanediol, 2-methyl-1,3-propanediol,3-methyl-1,5-pentanediol and 1,2,6-hexanetriol; alkylether acetates suchas polyethylene glycol monomethyl ether acetate; alkyl ethers of apolyhydric alcohol such as ethylene glycol monomethyl (or ethyl) ether,diethylene glycol methyl (or ethyl) ether and triethylene glycolmonomethyl (or ethyl) ether; N-methyl-2-pyrrolidone; 2-pyrrolidone and1,3-dimethyl-2-imidazolidinone. As a matter of course, the presentinvention is not limited to these. These water-soluble organic solventsmay be used alone or two or more types as needed.

(Other Additives)

The ink of the present invention may contain, other than the componentsmentioned above, water-soluble organic compounds solid at normaltemperature including polyhydric alcohols such as trimethylolpropane andtrimethylolethane and urea derivatives such as urea and ethylene urea,as needed. Furthermore, the ink of the present invention may containvarious types of additives such as a surfactant, a pH conditioner, anantirust agent, an antiseptic agent, an antifungal agent, anantioxidant, a reducing inhibitor, an evaporation accelerator, achelating agent and a water-soluble polymer, as needed.

<Other Types of Ink>

Furthermore, to record full-color images, the ink of the presentinvention can be used in combination with ink having different colortone from that of the ink of the present invention. The ink of thepresent invention can be used in combination with at least one type ofink selected from the group including black ink, cyan ink, magenta ink,yellow ink, red ink, green ink and blue ink. Also, the ink of thepresent invention can be used further in combination with ink havingsubstantially the same color tone, so called light-color ink. As thecoloring materials for these inks and light color ink that may be used,not only known dyes but also newly synthesized coloring materials may bementioned.

<Ink Jet Recording Method>

The ink jet recording method of the present invention is an ink jetrecording method in which recording is performed by ejecting inkaccording to an ink jet system and characterized in that the ink is theink jet ink of the present invention described above. The ink jetrecording method of the present invention can be applied, for example,to a recording method, in which ink is ejected by applying dynamicenergy to the ink, and to a recording method, in which ink is ejected byapplying thermal energy to the ink. Particularly, the ink jet recordingmethod using thermal energy can be applied to the present invention.

<Ink Cartridge>

The ink cartridge of the present invention is an ink cartridge having anink storage portion for storing ink and characterized in that the inkstored therein is the ink jet ink of the present invention describedabove.

<Recording Unit>

The recording unit of the present invention is a recording unit havingan ink storage portion for storing ink and a recording head for ejectingink and characterized in that the ink stored therein is the ink jet inkof the present invention described above. As examples of the recordingunit of the present invention that can be used include a system in whichthe recording head applies thermal energy to ink according to recordingsignals, thereby ejecting ink. Furthermore, in the present invention, amore desirable effect can be obtained by a recording head having aliquid surface in contact with a heat generating unit, containing ametal and/or a metal oxide. Specific examples of the metal and/or themetal oxide constituting the liquid surface in contact with the heatgenerating unit include a metal such as Ta, Zr, Ti, Ni or Al or oxidesof these metals.

<Ink Jet Recording Apparatus>

The ink jet recording apparatus of the present invention is an ink jetrecording apparatus having an ink storage portion for storing ink and arecording head for ejecting ink and characterized in that the ink storedtherein is the ink jet ink of the present invention described above. Asexamples of the ink jet recording apparatus of the present inventionthat can be used include a system in which the recording head appliesthermal energy to ink according to recording signals to eject ink.

Next, a schematic structure of machinery portion of an ink jet recordingapparatus according to the present invention will be described below.The ink jet recording apparatus includes a paper feed unit, a conveyanceunit, a carriage unit, a paper discharge unit, a cleaning unit eachnamed on the basis of the role of a mechanism, and a jacket whichprotects these units and contributes to design.

FIG. 1 is a perspective view of an ink jet recording apparatus.Furthermore, FIG. 2 and FIG. 3 are views illustrating the interiormechanism of the ink jet recording apparatus. FIG. 2 illustrates aperspective view thereof as viewed from the upper right portion and FIG.3 illustrates a longitudinal sectional view of the ink jet recordingapparatus.

In feeding a paper-sheet, from a paper feed unit including a paper-feedtray 2060, only a predetermined number of recording mediums are sent toa nip unit including a paper-feed roller 2080 and a separation roller2041. The recording medium is separated at the nip portion and theuppermost recording medium alone is conveyed. The recording mediumconveyed to the conveyance unit is guided by a pinch roller holder 3000and a paper guide flapper 3030 and conveyed to a pair of rollers,namely, a transfer roller 3060 and a pinch roller 3070. The pair ofrollers, the transfer roller 3060 and pinch roller 3070, are driven byan LF motor 2 to rotate. By the rotation, the recording medium istransferred onto a platen 3040.

In recording an image on the recording medium, the recording head 1001(FIG. 4; the detailed structure will be described later) is set at theposition for recording a target image by the carriage unit and therecording head ejects ink to the recording medium according to signalsfrom an electrical substrate 14. While recording is performed by therecording head 1001, the carriage 4000 moves in the raw direction in ascanning manner (main scanning) and the recording medium is moved by thetransfer roller 3060 in the line direction (sub scanning). By repeatingthe main scanning and the sub scanning alternately, an image is recordedon the recording medium. The recording medium on which the image isrecorded is fed while being sandwiched by the nip of a first paperdischarge roller 3110 and a spur 3120 in the paper discharge unit anddischarged to the paper discharge tray 3160.

Note that, the cleaning unit cleans the recording head 1001 before andafter recording an image. When a pump 5000 is actuated while theejection port of the recording head 1001 is capped with a cap 5010,unnecessary ink is suctioned from the ejection port of the recordinghead 1001. Furthermore, remaining ink in the cap 5010 is suctioned whilethe cap 5010 is opened. In this manner, sticking and other malfunctionscaused by the remaining ink can be prevented.

(Structure of Recording Head)

The structure of the head cartridge 1000 will be described. The headcartridge 1000 has the recording head 1001, a unit for installing an inkcartridge 1900 and a unit for supplying ink from the ink cartridge 1900to the recording head, and is installed detachably in the carriage 4000.

FIG. 4 is a view illustrating how to install the ink cartridge 1900 inthe head cartridge 1000. The ink jet recording apparatus records animage by use of each of yellow, magenta, cyan, black, light magenta,light cyan and green ink. Accordingly, the ink cartridge 1900 has sevenindependent color sections. Note that, as at least one ink of the aboveconstitution, the ink of the present invention is used. As illustratedin FIG. 4, individual ink cartridges are detachably attached to the headcartridge 1000. Note that, the ink cartridge 1900 can beattached/detached to the head cartridge 1000 installed in the carriage4000.

FIG. 5 is an exploded perspective view of the head cartridge 1000. Thehead cartridge 1000 includes a recording element substrate, a plate, anelectric wiring substrate 1300, a cartridge holder 1500, a flow-channelforming member 1600, a filter 1700, sealing rubber 1800, and so forth.The recording element substrate includes a first recording elementsubstrate 1100 and a second recording element substrate 1101. The plateincludes a first plate 1200 and a second plate 1400.

The first recording element substrate 1100 and the second recordingelement substrate 1101 are Si substrates. In one of the surfaces, aplurality of recording elements (nozzles) for ejecting ink arephotolithographically formed. Electric wiring formed of Al for supplyingelectric power to each of the recording elements is formed byfilm-formation technique, and a plurality of ink flow channelscorresponding to individual recording elements are formed byphotolithography. Furthermore, ink supply ports for supplying ink to theink flow channels are formed in the rear surface.

FIG. 6 is a magnified front view of the structure of the first recordingelement substrate 1100 and the second recording element substrate 1101.Reference numerals 2000 to 2600 represent recording elementscorresponding to different colors of ink arranged in line (hereinafteralso referred to as nozzle lines). In the first recording elementsubstrate 1100, three color nozzle lines, namely, a yellow ink nozzleline 2000, a magenta ink nozzle line 2100 and a cyan ink nozzle line2200, are formed. In the second recording element substrate 1101, fourcolor nozzle lines, namely, a light cyan ink nozzle line 2300, a blackink nozzle line 2400, a green ink nozzle line 2500 and a light magentaink nozzle line 2600, are formed.

Each nozzle line includes 768 nozzles arranged in the feed direction ofthe recording medium (sub scanning direction) at intervals of 1200 dpi(dot/inch; reference value) and ejects about 2 pico-liter of ink. Theopening area of each ejection port is set at about 100 μm². In thepresent invention, in view of photo-quality, the nozzle can eject smalldroplets of ink having a volume 5 pL or less, further 2 pL or less.Furthermore, the size of the ejection port can be less than 10 μm.Furthermore, to simultaneously attain good photo-quality and high-speedrecording, a plurality of nozzles (for example, 5 pL, 2 pL, 1 pL) forejecting different volumes of ink can be used in combination.

Next, referring to FIG. 4 and FIG. 5, the following will be described.The first recording element substrate 1100 and the second recordingelement substrate 1101 are adhered and fixed onto the first plate 1200,in which ink supply ports 1201 are formed for supplying ink to the firstrecording element substrate 1100 and the second recording elementsubstrate 1101. Furthermore, to the first plate 1200, a second plate1400 having opening portions is adhered and fixed. The second plate 1400holds the electric wiring substrate 1300 such that the electric wiringsubstrate 1300, the first recording element substrate 1100 and thesecond recording element substrate 1101 are electrically connected.

The electric wiring substrate 1300 applies electrical signals forejecting ink from each of the nozzles formed in the first recordingelement substrate 1100 and the second recording element substrate 1101.The electric wiring substrate 1300 has electrical wirings correspondingto the first recording element substrate 1100 and the second recordingelement substrate 1101, and an external signal input terminal 1301positioned at an end of the electrical wiring for receiving electricalsignals from the ink jet recording apparatus. The external signal inputterminal 1301 is positioned and fixed at the back surface of thecartridge holder 1500.

In the cartridge holder 1500 holding the ink cartridge 1900, the flowchannel forming member 1600 is fixed, for example, by ultrasonic fusionto form an ink flow channel 1501 from the ink cartridge 1900 to thefirst plate 1200. At the end of the ink flow channel 1501 near the sideat which the ink flow channel is engaged with the ink cartridge 1900, afilter 1700 is provided for preventing invasion of dust from theoutside. Furthermore, at the engaged portion with the ink cartridge1900, the sealing rubber 1800 is applied to prevent vaporization of inkfrom the engaged portion.

Furthermore, as mentioned above, the cartridge holder portion isconnected to the recording head 1001 by adhesive to form the headcartridge 1000. Note that, the cartridge holder portion includes thecartridge holder 1500, the flow channel forming member 1600, the filter1700 and the sealing rubber 1800. Furthermore, the recording head 1001includes the first recording element substrate 1100, the secondrecording element substrate 1101, the first plate 1200, the electricwiring substrate 1300 and the second plate 1400.

Note that, the recording head described herein as an embodiment is therecording head of a thermal ink jet system, in which recording isperformed by use of an electrothermal converter element (recordingelement), which produces thermal energy for causing film boiling of inkdepending upon the electrical signal. The typical structure andprinciple thereof are disclosed, for example, in U.S. Pat. Nos.4,723,129 and 4,740,796. This system can be applied not only to aso-called on-demand type but also a continuous type.

It is particularly effective to apply the thermal ink jet system to theon-demand type. In the case of the on-demand type, at least one drivingsignal, which provides a rapid increase of temperature exceeding nuclearboiling, corresponding to recording information, is applied to theelectrothermal converters arranged so as to correspond to liquid flowchannels for holding ink. In this way, thermal energy is generated fromthe electrothermal converter and causes film boiling of ink, with theresult that an air foam corresponding to the driving signal onone-on-one level can be formed in the ink. Ink is ejected through theejection port due to the growth and shrinkage of air foam, therebyforming at least one droplet. Use of a pulse form as the driving signalcan rapidly and appropriately grow or contract foams and consequentlycan eject ink with particularly excellent responsibility.

Furthermore, the ink of the present invention can be used not only in anink jet recording apparatus for the thermal ink jet system but also inan ink jet recording apparatus using dynamic energy as described below.The ink jet recording apparatus according to the embodiment includes anozzle forming substrate having a plurality of nozzles, pressuregenerating elements arranged so as to face the nozzles and formed of apiezoelectric material and a conductive material, and ink suppliedaround the piezoelectric materials. Voltage is applied to displace thepiezoelectric elements to eject ink from the nozzles.

The ink jet recording apparatus is not limited to the apparatus having arecording head and an ink cartridge separately arranged as describedabove. The apparatus in which they are unseparately integrated into onebody may be used. Furthermore, the ink cartridge may be separatelyarranged with the recording head or unseparately integrated with therecording head into one body and installed in the carriage, and furtherprovided to a predetermined site of the ink jet recording apparatus andsupplies ink through an ink supply member such as a tube to therecording head. Furthermore, when a structure for applying a desirablenegative pressure to the recording head is provided to the inkcartridge, the following structure may be employed. That is, thestructure in which an absorber is arranged in the ink storage portion ofthe ink cartridge or the structure in which a flexible ink storage bagand a spring unit for applying urge force in the direction of expandingthe inner volume may be employed. Furthermore, the ink jet recordingapparatus may employ a serial-type recording system. Besides this, theapparatus may employ a line-printer system in which recording elementsare arranged in light over the entire width of the recording medium.

EXAMPLES

The present invention will now be described in detail below withreference to examples and comparative examples. The present invention isnot limited by the following examples as long as the present inventiondoes not go beyond the scope of the invention. Note that, unlessotherwise specified, the units of ink components of Examples andComparative examples are “parts by mass”. Furthermore, the term “parts”and the symbol “%” in the description below are on the basis of mass,unless otherwise specified.

<Preparation of Coloring Material>

(Synthesis of Compound I-46)

As the compound I-46, a dye (lithium salt) synthesized according toExample 1 of Japanese Patent Application Laid-Open No. 2006-143989 wasused.

(Synthesis of compound III-1)

(A) To xylene (360 parts), a compound (94.8 parts) of the followingformula (1), sodium carbonate (3.0 parts) and ethyl benzoyl acetate(144.0 parts) were sequentially added while stirring. A reaction wasperformed for eight hours by increasing the temperature of the liquid to140 to 15° C. while removing ethanol and water generated during thereaction out of the reaction system by azeotropic distillation withxylene. After the reaction was terminated, the reaction liquid wascooled to a temperature of 30° C. To the reaction liquid, methanol (240parts) was added and stirred for 30 minutes. The resultant precipitatedsolid substance was obtained by filtration. The obtained solid substancewas washed with methanol (360 parts), and then dried to obtain acompound (124.8 parts) of the following formula (2) as a light yellowneedle-like crystal.

(B) To N,N-dimethylformamide (300.0 parts), the compound of the formula(2) (88.8 parts) obtained above, meta-aminoacetanilide (75.0 parts),copper acetate monohydrate (24.0 parts) and sodium carbonate (12.8parts) were sequentially added while stirring. Then, a reaction wasperformed for three hours by increasing the temperature of the liquid to120 to 130° C. The reaction liquid was cooled to about 50° C. andmethanol (120 parts) was added and stirred for 30 minutes. The resultantprecipitated solid substance was obtained by filtration. The obtainedsolid substance was washed with methanol (500 parts), subsequently withwarm water of 80° C., and then dried to obtain a compound (79.2 parts)of the following formula (3) as a bluish red crystal.

(C) To 98% sulfuric acid (130 parts), 28% fuming sulfuric acid (170parts) was added while cooling by water and while stirring to prepare a12% fuming sulfuric acid (300 parts). While cooling by water, thecompound (51.3 parts) of the formula (3) was added to this attemperature of 50° C. or less. Thereafter, the temperature of the liquidwas increased to 85 to 90° C. and a reaction was performed for fourhours. The reaction liquid was added to ice water (600 parts) whilesuppressing the temperature of the liquid from increasing by thegenerated heat by adding ice, thereby maintaining the temperature of theliquid at 40° C. or less. Next, water was added to the reaction liquidto obtain a liquid volume of 1,000 parts and filtration was performed toremove non-dissolved substances. To the mother liquid thus obtained,warm water was added up to 1,500 parts. While the liquid was maintainedat a temperature of 60 to 65° C., sodium chloride (300 parts) was addedand stirred for two hours. The precipitated crystal was obtained byfiltration. The obtained crystal was washed with a 20% aqueous sodiumchloride solution (300 parts) and sufficiently drained to obtain a wetcake (100.3 parts) containing a compound (59.2 parts) of the followingformula (4) as a red crystal.

(D) To water (60 parts), the wet cake (67.7 parts) of the compound ofthe formula (4) obtained above was added. Next, to this, a 25% aqueoussodium hydroxide solution (24 parts) was added and stirred to dissolvethe cake while adjusting the pH of the liquid to 3 to 4 by furtheradding the 25% aqueous sodium hydroxide solution. On the other hand, toice water (60 parts), Lipal OH (trade name, an anionic surfactant;manufactured by Lion Corporation)(0.4 parts) was added and furthercyanul chloride (8.9 parts) was added. The mixture was stirred for 30minutes to obtain a suspension solution. The obtained suspensionsolution was added to the solution containing the compound of theformula (4) obtained above. A reaction was performed at 25 to 30° C. forfour hours while maintaining the pH of the liquid at 2.7 to 3.0 by useof a 10% aqueous sodium hydroxide solution to obtain a reaction liquidcontaining a compound of the following formula (5).

(E) To the reaction liquid containing the compound of the formula (5)obtained above, sodium p-phenol sulfonate dihydrate (9.5 parts) wasadded. Subsequently, while maintaining the pH of the liquid at 6.5±0.3by adding a 25% aqueous sodium hydroxide solution to this, thetemperature of the liquid was increased to 50 to 55° C. and a reactionwas performed at the temperature for one hour to obtain a reactionliquid containing a compound of the following formula (6).

(F) To the reaction liquid containing the compound of the formula (6)obtained above, ethylenediamine (1.2 parts) was added. Subsequently,while maintaining the pH of the liquid at 7.8 to 8.2 by adding a 25%aqueous sodium hydroxide solution to this, the temperature of the liquidwas increased to 78 to 82° C. and a reaction was performed at thetemperature for one hour. Thereafter, water was added up to a liquidvolume of about 350 parts and filtration was performed to removenon-dissolved substances. To the mother liquid, water was added up to aliquid volume of 400 parts. While the temperature of the liquid wasmaintained at 55±2° C., concentrated hydrochloric acid was added toadjust the pH of the liquid to 3. Subsequently, to the liquid, sodiumhydrochloride (40 parts) was added for 15 minutes and stirred for 30minutes, and further concentrated hydrochloric acid was added to adjustthe pH of the liquid to 2. The resultant acidic aqueous solution wasstirred for one hour and the precipitated crystal was obtained byfiltration. The crystal thus obtained was washed with a 20% aqueoussodium chloride solution (100 parts) to obtain a red wet cake containingthe compound III-1 previously mentioned.

(G) The wet cake obtained above was added to methanol (500 parts). Theliquid was increased to a temperature of 60 to 65° C. and stirred forone hour. The precipitated crystal was obtained by filtration, washedwith methanol and dried to obtain the compound III-1 in the form of freeacid. The compound III-1 in the form of free acid thus obtained wasconverted into a sodium salt thereof by a general ion exchange method.

<Preparation of Ink>

Using the exemplified compounds I-46 and III-1 which are coloringmaterials obtained above, and C.I. Direct Red 227, C.I. Direct Red 52,C.I. Direct Blue 199, C.I. and Acid Yellow 23, inks were individuallyprepared as follows. First, the components shown in the upper columns ofTables 3 and 4 below were each mixed and sufficiently stirred.Thereafter, the mixture was filtrated under pressure by a filter havinga pore size of 0.2 μm to prepare inks according to Examples andComparative Examples. Note that, main characteristics of each ink arealso shown in the lower columns of Tables 3 and 4.

TABLE 3 Composition of ink and main characteristics (Unit of componentsshown in the upper columns: %) Example 1 2 3 4 5 Compound I-46 4.0 4.04.0 4.0 4.0 Compound III-1 Bis(2- 0.9 1.0 30.0 30.5 25.0hydroxyethyl)sulfone Glycerin 2-pyrrolidone 7.0 7.0 Urea Diethyleneglycol Triethylene glycol 1,5-pentanediol 10.0 10.0 Acetylenol E100 (*2)0.8 0.8 0.8 0.8 0.8 Water 77.3 77.2 65.2 64.7 70.2 Content A of 0.9 1.030.0 30.5 25.0 compound of general formula (II) [% by mass] Content B of0.0 0.0 0.0 0.0 0.0 glycerin [% by mass] A + B value 0.9 1.0 30.0 30.525.0 A/B value — — — — — Example 6 7 8 9 10 11 Compound I-46 4.0 4.0 4.04.0 4.0 4.0 Compound III-1 Bis(2- 6.0 4.0 3.0 6.0 10.0 6.0hydroxyethyl)sulfone Glycerin 0.9 3.0 5.0 5.0 5.0 2.0 2-pyrrolidone 5.07.0 7.0 5.0 5.0 7.0 Urea Diethylene glycol Triethylene glycol1,5-pentanediol 5.0 10.0 10.0 5.0 5.0 10.0 Acetylenol E100 (*2) 0.8 0.80.8 0.8 0.8 0.8 Water 78.3 71.2 70.2 74.2 70.2 70.2 Content A of 6.0 4.03.0 6.0 10.0 6.0 compound of general formula (II) [% by mass] Content Bof 0.9 3.0 5.0 5.0 5.0 2.0 glycerin [% by mass] A + B value 6.9 7.0 8.011.0 15.0 8.0 A/B value 6.67 1.33 0.60 1.20 2.00 3.00 Example 12 13 1415 16 17 Compound I-46 4.0 4.0 4.0 4.0 4.0 4.0 Compound III-1 Bis(2-19.0 18.5 6.0 3.0 2.3 6.4 hydroxyethyl)sulfone Glycerin 4.0 5.0 20.5 8.05.9 16.0 2-pyrrolidone 5.0 5.0 5.0 7.0 5.0 Urea Diethylene glycolTriethylene glycol 1,5-pentanediol 5.0 5.0 5.0 10.0 5.0 Acetylenol E100(*2) 0.8 0.8 0.8 0.8 0.8 0.8 Water 62.2 71.7 58.7 74.2 70.0 62.8 ContentA of 19.0 18.5 6.0 3.0 2.3 6.4 compound of general formula (II) [% bymass] Content B of 4.0 5.0 20.5 8.0 5.9 16.0 glycerin [% by mass] A + Bvalue 23.0 23.5 26.5 11.0 8.2 22.4 A/B value 4.75 3.70 0.29 0.38 0.390.40 Example 18 19 20 21 22 23 Compound I-46 4.0 4.0 4.0 1.5 1.5 1.5Compound III-1 4.5 4.5 4.5 Bis(2- 17.7 19.7 13.8 10.0 10.0 10.0hydroxyethyl)sulfone Glycerin 3.0 3.3 2.3 5.0 5.0 5.0 2-pyrrolidone 5.05.0 5.0 5.0 Urea 5.0 Diethylene glycol 5.0 5.0 Triethylene glycol 5.01,5-pentanediol 5.0 5.0 5.0 5.0 Acetylenol E100 (*2) 0.8 0.8 0.8 0.8 0.80.8 Water 64.5 62.2 69.1 68.2 68.2 68.2 Content A of 17.7 19.7 13.8 10.010.0 10.0 compound of general formula (II) [% by mass] Content B of 3.03.3 2.3 5.0 5.0 5.0 glycerin [% by mass] A + B value 20.7 23.0 16.1 15.015.0 15.0 A/B value 5.90 5.97 6.00 2.00 2.00 2.00 (*2) Acetylene glycolethylene oxide adduct (Surfactant; manufactured by Kawaken FineChemicals Co., Ltd.)

TABLE 4 Composition of ink and main characteristics (Unit of componentsshown in the upper columns: %) Comparative Example 1 2 3 4 5 CompoundI-46 4.0 4.0 4.0 C.I. Direct Red 227 5.0 C.I. Direct Red 52 10.0 C.I.Direct Blue 199 C.I. Acid Yellow 23 Bis(2- 30.0 5.0 hydroxyethyl)sulfoneGlycerin 2-pyrrolidone 7.0 N-methyl-2-pyrrolidone 10.0 Ethylene urea30.5 23.5 0.9 Diethylene glycol Polyethylene glycol (*1) 1,5-pentanediol10.0 1,6-hexanediol 1,2,6-hexanetriol Isopropyl alcohol 10.0 Trimethylolpropane Ethylene glycol 10.0 monomethyl ether Tetraethylene glycolmonobutyl ether Acetylenol E100 (*2) 0.8 0.8 0.8 0.8 0.8 Water 64.7 71.777.3 54.2 64.2 Content A of compound 0.0 0.0 0.0 30.0 5.0 of generalformula (II) [% by mass] Content B of glycerin 0.0 0.0 0.0 0.0 0.0 [% bymass] A + B value 0.0 0.0 0.0 30.0 5.0 A/B value — — — — — ComparativeExample 6 7 8 9 10 11 Compound I-46 5.0 C.I. Direct Red 227 C.I. DirectRed 52 5.0 C.I. Direct Blue 199 4.0 4.0 5.0 C.I. Acid Yellow 23 3.0 4.0Bis(2- 12.0 10.0 5.0 3.0 5.0 hydroxyethyl)sulfone Glycerin 2.0 14.0 13.07.0 2-pyrrolidone N-methyl-2-pyrrolidone 10.0 Ethylene urea Diethyleneglycol 9.0 Polyethylene glycol (*1) 10.0 3.0 1,5-pentanediol1,6-hexanediol 5.0 7.0 1,2,6-hexanetriol 7.0 Isopropyl alcoholTrimethylol propane 3.0 Ethylene glycol 10.0 monomethyl etherTetraethylene glycol 9.0 monobutyl ether Acetylenol E100 (*2) 0.8 0.80.8 0.8 0.8 0.8 Water 74.2 66.2 68.2 74.2 69.2 69.2 Content A ofcompound 12.0 10.0 5.0 3.0 0.0 5.0 of general formula (II) [% by mass]Content B of glycerin 2.0 14.0 13.0 0.0 7.0 0.0 [% by mass] A + B value14.0 24.0 18.0 3.0 7.0 5.0 A/B value 6.00 0.71 0.38 — 0.00 — (*1)Average molecular weight 200 (*2) Acetylene glycol ethylene oxide adduct(Surfactant; manufactured by Kawaken Fine Chemicals Co., Ltd.)

<Evaluation>

(1) Color Tone

Each of the inks obtained in the above was set at an ink jet recordingapparatus (trade name: PIXUS iP8600; manufactured by Canon Inc.) usingthermal energy. Recording conditions were set at as follows:temperature: 23° C., relative humidity: 55%, recording density: 2,400dpi×1,200 dpi, ejection volume: 2.5 pL. An image was recorded on arecording medium (trade name: PR-101; manufactured by Canon Inc.) whilechanging the recording duty from 0% to 100% at 10% intervals. The imagewas allowed to naturally dry at a temperature of 23° C. and a relativehumidity of 55% for 24 hours. In the recorded matter thus obtained, aportion of an image having a recording duty of 100% was measured for a*and b* of the L*a*b* display system defined by the CIE (CommissionInternationale de l'Eclairage (International Commission onIllumination)) to evaluate color tone. Note that, a* and b* weremeasured by a spectrophotometer (Spectorolino; manufactured by GretagMacbeth) in the conditions: light source: D50, field of vision: 2°. Onthe basis of the values of a* and b* thus obtained and the followingequation (A), each of hue angles (H°) was calculated to evaluate colortone (hue angle). The evaluation criteria of color tone (hue angle) areas follows. The evaluation results are shown in Table 5. In the presentinvention, of the criteria below, B is ink having a color tone ofmagenta that can be used, A is ink having the color tone of magentawhich can be particularly used and C is ink having unacceptable colortone of magenta.

In a*≧0, b*≧0 (first quadrant), H°=tan⁻¹(b*/a*)

In a*≦0, b*≧0 (second quadrant), H°=180+tan⁻¹(b*/a*)

In a*≦0, b*≦0 (third quadrant), H°=180+tan⁻¹(b*/a*)

In a*≧0, b*≦0 (fourth quadrant), H°=360+tan⁻¹⁽ b*/a*)   Equation (A)

-   A: H° is 0 or more and 5 or less-   B: H° is more than 5 and 50 or less, or 350 or more and less than    360-   C: H° is more than 50 and less than 350

(2) Lightfastness

Each of the inks obtained in the above was set at an ink jet recordingapparatus (trade name: PIXUS iP8600; manufactured by Canon Inc.) usingthermal energy. Recording conditions were set at as follows:temperature: 23° C., relative humidity: 55%, recording density: 2,400dpi×1,200 dpi, ejection volume: 2.5 pL. An image was recorded on arecording medium (trade name: PR-101; manufactured by Canon Inc.) whilechanging a recording duty from 0% to 100% at 10% intervals. The imagewas allowed to naturally dry at a temperature of 23° C. and a relativehumidity of 55% for 24 hours. In the recorded matter thus obtained, aportion of an image having a recording duty of 100% was measured foroptical density (this is the “optical density before the test”).Furthermore, the recorded matter was exposed to light by use of a superxenon testing machine (trade name: SX-75; manufactured by Suga TestInstruments Co., Ltd.) in the conditions: irradiation intensity: 100klux, inner vessel temperature: 24° C., relative humidity: 60%, for 168hours. Thereafter, the portion of the image of the recorded matterhaving a recording duty of 100% was measured for optical density (thisis the “optical density after the test”). Note that, the optical densitywas measured by a spectrophotometer (Spectorolino; manufactured byGretag Macbeth) under the conditions: light source: D50, field of view:2°. On the basis of the values of the optical density before the testand optical density after the test and the following equation, aresidual optical density rate was calculated to evaluate lightfastness.The evaluation criteria of lightfastness are as follows. The evaluationresults are shown in Table 5. In the present invention, of the criteriabelow, B is an acceptable level, A is an excellent level, and C is anunacceptable level because the degree of color fading of an image afterthe lightfastness test is large.

${{Residual}\mspace{14mu} {optical}\mspace{14mu} {density}\mspace{14mu} {{rate}\lbrack\%\rbrack}} = {\frac{{Optical}\mspace{14mu} {density}\mspace{14mu} {after}{\mspace{11mu} \;}{test}}{{Optical}\mspace{14mu} {density}\mspace{14mu} {before}\mspace{14mu} {test}} \times 100}$

-   A: Residual optical density rate is 80% or more-   B: Residual optical density rate is 70% or more and less than 80%-   C: Residual optical density rate is less than 70%

(3) Intermittent Ejection Stability

Each of the inks obtained in the above was set at an ink jet recordingapparatus (trade name: PIXUS iP8600; manufactured by Canon Inc.) usingthermal energy. The ink jet recording apparatus was allowed to standunder the environment of a temperature of 15° C. and a humidity of 10%RH, for five hours or more and ink was allowed to eject from apredetermined nozzle in the same environment. Thereafter, the nozzle wasnot used for a predetermined time and again ink was allowed to ejectfrom the nozzle to record an image on a recording medium (trade name:HR-101; manufactured by Canon Inc.). The image thus obtained wasvisually observed to evaluate intermittent ejection stability. Theevaluation criteria of intermittent ejection stability are as follows.The evaluation results are shown in Table 5. In the present invention,of the criteria below, C or more is defined as sufficient intermittentejection stability, B as excellent intermittent ejection stability and Aas particularly excellent intermittent ejection stability and D as anunacceptable level.

-   A: Normal recording was performed even after the nozzle was not used    for five seconds-   B: Normal recording was performed even after the nozzle was not used    for three seconds-   C: Slight deterioration of the recording quality was observed after    the nozzle was not used for three seconds but no problem was posed-   D: Ejection failure or irregular recording was observed after the    nozzle was not used for three seconds

(4) Sticking Resistance

Each of the inks obtained in the above was set at an ink jet recordingapparatus (trade name: PIXUS iP8600; manufactured by Canon Inc.) usingthermal energy. After the ink jet recording apparatus was cleaned, anozzle check pattern of PIXUS iP8600 was recorded. Thereafter, apower-source cable was pulled out while the carriage was moving tocreate the state where the recording head was not capped. While keepingthis state, the ink jet recording apparatus was allowed to stand stillin the environment of a temperature of 30° C. and a humidity of 10% RHfor 14 days. Thereafter, the ink jet recording apparatus was allowed tostand in the environment of a temperature of 25° C. for six hours andreturned to normal temperature. Then, recording was performed by the inkjet recording apparatus while cleaning it, sticking resistance wasevaluated. The evaluation criteria of the sticking resistance are asfollows. The evaluation results are shown in Table 5. In the presentinvention, of the criteria below, B or more is defined as sufficientsticking resistance, A as particularly excellent sticking resistance andC as an unacceptable level.

-   A: Normal recording was performed by performing a cleaning operation    once or twice-   B: Normal recording was performed by performing a cleaning operation    3 to 10 times-   C: Normal recording was not performed by performing a cleaning    operation 10 times or less

(5) Recording Durability

Each of the inks obtained in the above was set at an ink jet recordingapparatus (trade name: PIXUS iP3100; manufactured by Canon Inc.) usingthermal energy. After a predetermined number of electric pulses wasapplied to the heater of the recording head, a PIXUS iP3100 nozzle checkpattern was recorded. The nozzle check pattern thus obtained wasvisually confirmed to evaluate recording durability. Note that if thenozzle check pattern obtained after application of the predeterminednumber of electric pulses is normally recorded, it was demonstrated thatno wire breakage of the heater occurred. The evaluation criteria of therecording durability are as follows. The evaluation results are shown inTable 5. In the present invention, of the criteria below, B or more isdefined as sufficient recording durability, A as particularly excellentheater durability and C as an unacceptable level.

-   A: No wire breakage of the heater occurred even if a pulse of    2.0×10⁸ was applied-   B: Wire breakage of the heater occurred by applying a pulse of    1.5×10⁸ or more to 2.0×10⁸ or less-   C: Wire breakage of the heater occurred by applying a pulse of less    than 1.5×10⁸

TABLE 5 Evaluation results Intermittent Color Light- Recording Stickingejection tone fastness durability resistance stability Example 1 B B B BB Example 2 B A B B B Example 3 B A B B B Example 4 B A B B C Example 5B A B B B Example 6 B A B A B Example 7 B A B A B Example 8 B A A A AExample 9 B A A A A Example 10 B A A A A Example 11 B A A A A Example 12B A A A A Example 13 B A B A B Example 14 B A B A B Example 15 B A B A AExample 16 B A A A B Example 17 B A A A A Example 18 B A A A A Example19 B A A A B Example 20 B A B A A Example 21 A A A A A Example 22 A A AA A Example 23 A A A A A Comparative B C B B D Example 1 Comparative B CB B C Example 2 Comparative B C B B C Example 3 Comparative B C C B DExample 4 Comparative B C B C C Example 5 Comparative C C A B B Example6 Comparative C C C A B Example 7 Comparative C C B A B Example 8Comparative C C C B B Example 9 Comparative B C B B C Example 10Comparative B C B B B Example 11

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2008-072277, filed Mar. 19, 2008, which is hereby incorporated byreference herein in its entirety.

1. An ink jet ink comprising at least a compound represented by thefollowing general formula (I) and a compound represented by thefollowing general formula (II):

wherein, in general formula (I), [A] is a 5-membered heterocyclic group;[B] and [C] are CR₁ and CR₂ or one of [B] and [C] is a nitrogen atom andthe other is CR₁; and R₅ and R₆ are each independently a hydrogen atomor a substituent selected from the group including an aliphatic group,an aromatic group, a heterocyclic group, an acyl group, analkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, analkylsulfonyl group, an arylsulfonyl group and a sulfamoyl group; ahydrogen atom of the substituent may be substituted; R₁ and R₂ that canpartly constitutes [B], [C] and [D] in the formula are eachindependently a hydrogen atom or a substituent selected from the groupincluding a halogen atom, an aliphatic group, an aromatic group, aheterocyclic group, a cyano group, a carboxy group, a carbamoyl group,an alkoxycarbonyl group, an aryloxycarbonyl group, a heterocyclicoxycarbonyl group, an acyl group, a hydroxyl group, an alkoxy group, anaryloxy group, a heterocyclic oxy group, a silyloxy group, an acyloxygroup, a carbamoyloxy group, an alkoxycarbonyloxy group, anaryloxycarbonyloxy group, an amino group, an acylamino group, a ureidogroup, a sulfamoylamino group, an alkoxycarbonylamino group, anaryloxycarbonylamino group, an alkylsulfonylamino group, anarylsulfonylamino group, a heterocyclic sulfonylamino group, a nitrogroup, an alkylthio group, an arylthio group, a heterocyclic thio group,an alkylsulfonyl group, an arylsulfonyl group, a heterocyclic sulfonylgroup, an alkylsulfinyl group, an arylsulfinyl group, a heterocyclicsulfinyl group, a sulfamoyl group, and a sulfonic acid group; a hydrogenatom of the substituent may be substituted and R₁ and R₅ or R₅ and R₆may be joined to form a 5-membered ring or a 6-membered ring); andR_(x)-[E]-R_(y)   General formula (II) wherein, in general formula (II),-[E]- is —S—, —S(═O)— or —S(═O)₂—; R_(x) and R_(y) are eachindependently one selected from the group including a hydrogen atom, ahydroxyl group, an alkyl group, a hydroxyalkyl group, an alkenyl group,an acyl group, a carbamoyl group, a carboxy group and a sulfonyl group,with the proviso that R_(x) and R_(y) may not simultaneously takehydrogen atoms or hydroxyl groups or an hydrogen atom and a hydroxylgroup.
 2. The ink jet ink according to claim 1, wherein a content (% bymass) of a compound represented by the general formula (II) in the inkis in the range of 1.0% by mass to 30.0% by mass with respect to a totalmass of the ink.
 3. The ink jet ink according to claim 1, wherein thecompound represented by the general formula (II) isbis(2-hydroxyethyl)sulfone.
 4. The ink jet ink according to claim 1,further comprising glycerin.
 5. The ink jet ink according to claim 4,wherein the sum of the content of the compound represented by thegeneral formula (II) (% by mass) and the content of glycerin (% by mass)with respect to a total mass of the ink is 8.0% by mass to 23.0% bymass.
 6. The ink jet ink according to claim 4, wherein the mass ratio ofthe content of the compound represented by the general formula (II) tothe content of glycerin is in the range of 0.40 or more to 5.90 or less.7. The ink jet ink according to claim 1, further comprising a compoundrepresented by the following general formula (III), wherein the massratio of the content of the compound represented by the followinggeneral formula (III) to the content of the compound represented by thegeneral formula (I) is 2.5 or more to 10.0 or less:

wherein, in general formula (III), R_(z)(s) are each independently ahydrogen atom, an alkyl group, a hydroxyalkyl group, a cyclohexyl group,a monoalkylaminoalkyl group or dialkylaminoalkyl group; M(s) are eachindependently one selected from the group including a hydrogen atom, analkali metal, ammonium and organic ammonium; and [F] is a linking group.8. An ink jet recording method in which recording is performed byejecting ink by an ink jet system, wherein the ink comprises the ink jetink according to claim
 1. 9. An ink cartridge comprising an ink storageportion for storing ink, wherein the ink comprises the ink jet inkaccording to claim
 1. 10. A recording unit comprising an ink storageportion for storing ink and a recording head for ejecting ink, whereinthe ink comprises the ink jet ink according to claim
 1. 11. An ink jetrecording apparatus comprising an ink storage portion for storing inkand a recording head for ejecting ink, wherein the ink comprises the inkjet ink according to claim 1.